Preguntas Test Surface Engineering

The segregation coefficient of an acceptor impurity in a semiconductor represents: The maximum possible acceptor concentration in the semiconductor in liquid phase. T. F.

The segregation coefficient of an acceptor impurity in a semiconductor represents: The minimum possible acceptor concentration in the semiconductor in solid phase. T. F.

The segregation coefficient of an acceptor impurity in a semiconductor represents: The acceptor concentration ratio between solid and liquid phases of the semiconductor. T. F.

The segregation coefficient of an acceptor impurity in a semiconductor represents: The efficiency of the acceptor to incorporate to the semiconductor when grown by LPE. T. F.

The segregation coefficient of an acceptor impurity in a semiconductor represents: The efficiency of the acceptor to incorporate to the semiconductor when grown by MBE. T. F.

Consider a homoepitaxial growth of a GaAs layer on a GaAs substrate by MBE: The growth can proceed at any pressure above 10-4 Torr. T. F.

Consider a homoepitaxial growth of a GaAs layer on a GaAs substrate by MBE: The type of surface reconstruction during growth is not related to the layer quality. T. F.

Consider a homoepitaxial growth of a GaAs layer on a GaAs substrate by MBE: All atoms/molecules arriving to the substrate surface will incorporate into the crystal. T. F.

Consider a homoepitaxial growth of a GaAs layer on a GaAs substrate by MBE: If an Al flux equal to that of Ga is added, the resulting alloy will always be Ga0.5Al0.5As. T. F.

Consider a homoepitaxial growth of a GaAs layer on a GaAs substrate by MBE: If we add a dopant flux (Be) the resulting hole concentration will not depend on the growth rate. T. F.

Considering an epitaxial growth of Silicon by VPE: There is no limit of growth rate as a function of the (SiCl4) mole fraction in the gas phase. T. F.

Considering an epitaxial growth of Silicon by VPE: The growth process can be reversed to etch and clean the silicon surface. T. F.

Considering an epitaxial growth of Silicon by VPE: The growth rate always increases with the growth temperature. T. F.

Considering an epitaxial growth of Silicon by VPE: The activation energy represents the minimum energy needed to pyrolize the precursors. T. F.

Considering an epitaxial growth of Silicon by VPE: The boundary layer determination is only possible for a laminar flux regime. T. F.

Considering a diffusion process: The impurity concentration value at the surface never changes with time. T. F.

Considering a diffusion process: The impurity concentration can have any type of profile. T. F.

Considering a diffusion process: The junction depth always depends critically on the doping level of the substrate. T. F.

Considering a diffusion process: An intrinsic diffusion at a given T may become extrinsic at higher temperature. T. F.

Considering a diffusion process: An extrinsic diffusion at a given T will always be extrinsic at higher temperatures. T. F.

In a process of doping by ion implantation: For any ion the dominant stopping power increases monotonically with the acceleration energy. T. F.

In a process of doping by ion implantation: The dominant stopping power at high energy is always electronic. T. F.

In a process of doping by ion implantation: The stopping power efficiency depends on the substrate crystal orientation. T. F.

In a process of doping by ion implantation: The damage produced is always higher near the substrate surface. T. F.

In a process of doping by ion implantation: There is an independent control of impurity dose and average depth. T. F.

In a silicon substrate during an etching process: Anisotropy depends fundamentally on the temperature. T. F.

In a silicon substrate during an etching process: Etching rate is always the same for all crystalline planes. T. F.

In a silicon substrate during an etching process: Wet etching is always anisotropic. T. F.

In a silicon substrate during an etching process: Dry etching is never selective. T. F.

In a silicon substrate during an etching process: Selectivity and anisotropy can be achieved simultaneously by wet etching. T. F.

When growing bulk semiconductor crystals: Doping profiles are always uniform. T. F.

When growing bulk semiconductor crystals: Doping level is dependent on the growth rate. T. F.

When growing bulk semiconductor crystals: The effective segregation coefficient can be made close to one. T. F.

When growing bulk semiconductor crystals: The effective segregation coefficient can be higher than one. T. F.

When growing bulk semiconductor crystals: Their crystal quality is comparable to that of epitaxial layers. T. F.

Considering a diffusion process: The impurity concentration can have any type of profile. T. F.

Considering a diffusion process: The junction depth always depends critically on the doping level of the substrate. T. F.

Considering a diffusion process: An intrinsic diffusion at a given T may become extrinsic at higher temperature. T. F.

In an ion implantation process: Channeling effects are reduced by tilting the substrate at a given angle related to the ion beam. T. F.

In an ion implantation process: Transversal and projected straggles (σp, σ┴) always increase with ion energy. T. F.

In an ion implantation process: The projected range is always bigger than the straggle σp for a given ion. T. F.

In an ion implantation process: The crystal damage is increased when performed at higher temperature than RT. T. F.

In an ion implantation process: The mask thickness required depends on ion energy but not on the ion used. T. F.

In a thermal oxidation process of Silicon: The impurity concentration profiles existing in the substrate do not change after oxidation. T. F.

In a thermal oxidation process of Silicon: The thickness of consumed silicon is always 20% of the total thickness. T. F.

In a thermal oxidation process of Silicon: The existence of a previous SiO2 thickness does not affect the oxidation growth rate. T. F.

In a thermal oxidation process of Silicon: Wet oxidation is faster than dry oxidation when performed at the same temperature. T. F.

In a thermal oxidation process of Silicon: SiO2 can be deposited by PA- CVD at lower temperatures than by thermal oxidation. T. F.

In a lithographic process: Positive and negative resists give the same result when using the same mask. T. F.

In a lithographic process: The resolution by projection method is always much worse than by proximity. T. F.

In a lithographic process: The optimal photo-resist thickness is independent on the optics focusing depth. T. F.

In a lithographic process: The yield (productivity) is not dependent on the device size for a given cleanliness class. T. F.

In a lithographic process: Illumination power density threshold is always the same for positive and negative resists. T. F.

In an etching process: Wet etching provides always selectivity and anisotropy. T. F.

In an etching process: Etching rate is never dependent on the crystal planes in wet etching. T. F.

In an etching process: Etching rate is never dependent on crystal planes in sputtering dry etching (ion Milling). T. F.

In an etching process: Etch undercut below the mask is always much smaller than the vertical etch depth for wet etch. T. F.

In an etching process: Dry etching by ion Milling generally gives good selectivity. T. F.

For a given semocinductor material: the value of the intrinsic carrier concentration (ni) depends only on temperature. T. F.

For a given semocinductor material: the value of ni always represents the concentration of electrons and holes. T. F.

For a given semocinductor material: the value of ni always establishes the relation between electorn and hole concentration. T. F.

For a given semocinductor material: the value of the energy gap changes linearly with the temperature. T. F.

For a given semocinductor material: its intrinsic or extrinsic character does not depend on the temperature. T. F.

Consider the growth of a doped silicon ingot by Czochraslki method: the doping profile will always be homogeneous along the crystal length. T. F.

Consider the growth of a doped silicon ingot by Czochraslki method: the doping profile will always be inhomogeneous algon the radial direction. T. F.

Consider the growth of a doped silicon ingot by Czochraslki method: the n- type and p- type doping profiles will always be homogeneous and inhomogeneous, respecitvely. T. F.

Consider the growth of a doped silicon ingot by Czochraslki method: the growth rate will affect both n- and p-type doping profiles. T. F.

Consider the growth of a doped silicon ingot by Czochraslki method: the n-type doping profile is always more homogeneous than the p-type one. T. F.

Consider a homoepitaxial growth of GaAS layer on GaAs substrate by LPE: the typical growth temperature range always stays above 1000ºC. T. F.

Consider a homoepitaxial growth of GaAS layer on GaAs substrate by LPE: the AS desorption from the melt must always be considered and counter balanced. T. F.

Consider a homoepitaxial growth of GaAS layer on GaAs substrate by LPE: GaAs epilayers as thin as 2 nm can typically be obtained. T. F.

Consider a homoepitaxial growth of GaAS layer on GaAs substrate by LPE: GaAs epilayer thickness above 1 micron always generate dislocations in it. T. F.

Consider a homoepitaxial growth of GaAS layer on GaAs substrate by LPE: the growth process is possible from a low Ga% dissolved in melted As. T. F.

Considering an hepitaxial growth of GaAs by MBE: it can take place at atmospheric pressure. T. F.

Considering an hepitaxial growth of GaAs by MBE: the constituent atoms always incorporate to the crystal after a pyrolisis processF. T. F.

Considering an hepitaxial growth of GaAs by MBE: the constituent atoms arriving to the substrate always get into the crystal. T. F.

Considering an hepitaxial growth of GaAs by MBE: the doping level achievable does not depend on the doping level. T. F.

Considering an hepitaxial growth of GaAs by MBE: the growth rate depends on the doping level. T. F.

Considering an hepitacial growth of silicon by VPE: the growth rate is always linear with the mole fraction of the precursor (SiCl4). T. F.

Considering an hepitacial growth of silicon by VPE: the growth rate can be zero for certain values of the precursor mole fraction. T. F.

Considering an hepitacial growth of silicon by VPE: the optimal regime is that corresponding to a limitation by reaction (kinetic). T. F.

When growing a bulk semiconductor crystal: Czochralski method proceeds at the semiconductor melting temperature. T. F.

When growing a bulk semiconductor crystal: Floating zone method proceeds at much lower temperatures than the semiconductor melting one. T. F.

When growing a bulk semiconductor crystal: Doping in floating zone method is done by dissolving dopant species previously in the melt. T. F.

When growing a bulk semiconductor crystal: Bridgman method is applicable to grow all semiconductors. T. F.

When growing a bulk semiconductor crystal: Liquid encapsulated Czochralski method is typically used to grow GaAs ingots. T. F.

When growing epitaxial semiconductor layers: LPE is easy to scale up for production. T. F.

When growing epitaxial semiconductor layers: MBE provides the highest material quality due to its thermodynamic equilibrium nature. T. F.

When growing epitaxial semiconductor layers: MBE may use, either solid, or gas sources. T. F.

When growing epitaxial semiconductor layers: both VPE and LPE are methods that allow high growth rates compared to BE. T. F.

When growing epitaxial semiconductor layers: MOVPE is a method thay always uses precursors in gas phase. T. F.

Lithography: photoresist removal is never performed by plasma etching. T. F.

Lithography: electron beam lithography commonly requires a thinner resist layer than optical lithography. T. F.

Lithography: step-and-repeat systems are typically compatible wiht high NA optics and immersion lithography. T. F.

Lithography: the resolution of a lithography system typically improves when using particles with more mass than photons. T. F.

Lithography: the exposed area in the mask depends on the type of resist selected (positive/negative). T. F.

Metallization process: in a lift-off porcess, the photoresist thickness mist be considered when depositing a metal on top. T. F.

Metallization process: DC plasma sputtering is limited by the target material properties. T. F.

Metallization process: the threshold energy for sputtering depends on the final substance properties. T. F.

Metallization process: magnetic fields can be used to increase the required energy to start the sputtering process. T. F.

Metallization process: sputtering metallization susytems always require better vacuum systems than e-beam metal evaporators. T. F.

Etch process: Wet etching is typically isotropic in amorphous layers. T. F.

Etch process: the HNA etching rate can be controlled by the solvent proportion. T. F.

Etch process: HF in HNA acts s an oxide solvent. T. F.

Etch process: TMAH wet etching is not used for CMOS fabrication. T. F.

Etch process: reactive ion etching can be tailored for isotropic layer removal. T. F.