Behavior of Damage in Selectively Implanted SiGe/Si

AbstractEpitaxial SiGe/Si layers are being extensively investigated for use in base regions of high-speed heterojunction bipolar-transistors (HBTs). Extended defects can be formed in SiGe/Si layers by ion-implantation. Defects, once formed in the layers, can negatively impact electrical performance and also future reliability of the HBTs. The present study investigates the interaction between selective-implant damage and strained SiGe/Si layers of sub-critical thickness. Implant-damage is observed to form dislocation-sources at the edges of implanted regions in SiGe/Si heterolayers. The dislocation sources produce glide dislocation loops. Segments of these loops glide down to SiGe/Si interfaces causing misfit dislocations to arise at interfaces in the heterolayers. Misfitdislocations are formed in directions parallel to and perpendicular to the <110> edge of the implanted region. Dislocations propagate out to a distance of ∼100-150 nm past the edge of the implant in the case of Si0.9Ge0.1/Si layers of sub-critical thickness. The origin and behavior of these defects is discussed.

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Microstructural Characterization of SiGe Heterolayers

MRS Proceedings ◽

10.1557/proc-239-437 ◽

1991 ◽

Vol 239 ◽

Author(s):

N. David Theodore ◽

Peter Fejes ◽

Mamoru Tomozane ◽

Ming Liaw

Keyword(s):

Heterojunction Bipolar Transistors ◽

Infrared Detectors ◽

Field Effect ◽

Strain Energy ◽

Field Effect Transistors ◽

Microstructural Characterization ◽

Bipolar Transistors ◽

Misfit Dislocations ◽

Extended Defects

ABSTRACTSiGe is of interest for use in heterojunction-bipolar transistors, infrared detectors and field-effect transistors. In this study, graded SiGe heterolayers grown on Si, and heterolayers grown on SIMOX by CVD, were characterized using TEM. The graded-heterolayers consisted of ten layers of Si1-xGex on substrate silicon. Misfit dislocations were present at interfaces in the bottom 4–5 layers of the heterostructure. This conforms with predictions from qualitative strain-energy considerations. The greatest density of misfit dislocations was present at the Si1-xGex interface between the bottom two layers of the heterostructure. Dislocations were observed to extend out of the interface and up into the heterolayer structure. The defects were found to interact with interfaces in the structure and finally cease extending upwards towards the surface of the wafer. In addition to graded heterolayers, SiGe heterolayers grown on SIMOX were also investigated. The structures consisted of epi-silicon grown on a Si/Si1-xGex superlattice which was in turn grown on a Si/SiO2 (SIMOX) structure. The behavior of defects in the layers was of interest. TEM characterization showed a large density of extended-defects present in the layers. Dislocations were observed to originate at the SIMOX oxide/Si interface, propagate up through the SiGe superlattice and into the epi-Si layer. Some dislocations were found to interact with the SiGe superlattice and cease propagating up towards the top of the wafer. SiGe superlattices with a higher concentration of Ge are more effective in reducing defect propagation towards the surface of the wafer.

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Stress-Related Defects in Implanted Locos + Trench - Isolated Structures

MRS Proceedings ◽

10.1557/proc-262-725 ◽

1992 ◽

Vol 262 ◽

Cited By ~ 2

Author(s):

Barbara Vasquez ◽

N. David Theodore

Keyword(s):

Stress Fields ◽

High Dose ◽

Extended Defects ◽

Dislocation Loops ◽

Defect Engineering ◽

Local Oxidation ◽

Trench Isolation ◽

And Behavior ◽

Dislocation Sources ◽

Reducing Stress

ABSTRACTPoly-buffered local-oxidation of silicon + trench-isolation (PBLT) is a technique being explored for device isolation. In an earlier study, we had reported the presence of dislocations associated with a combination of high-dose (∼5E14 cm2) phosphorous implants and PBLT isolation. In the present study, the behavior of extended defects present in the structures is analyzed in greater detail. The origin and behavior of the defects is modelled to explore potential mechanisms to explain the observations. Implantation induced dislocation-loops interact with stress fields associated with PBLT isolation-trenches. Some of the implant loops (in the presence of a stress field) transform to dislocation sources which then create glide dislocations in the structures. Strategies for defect engineering are discussed, including reducing implant-induced damage (lowering the implant dose) or reducing stress fields (by moving the edge of the implanted region away from the trench). Defect densities can be reduced or eliminated.

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TEM evaluation of graded SixGe1-x heterolayers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088786 ◽

1991 ◽

Vol 49 ◽

pp. 894-895

Author(s):

N. David Theodore ◽

Mamoru Tomozane ◽

Ming Liaw

Keyword(s):

Heterojunction Bipolar Transistors ◽

Gas Flow ◽

Field Effect Transistors ◽

Chemical Vapor ◽

Dark Field ◽

Bipolar Transistors ◽

Structural Quality ◽

Weak Beam ◽

Transmission Electron ◽

And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

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TEM study of phosphorus-implanted pseudomorphic Si0.88Ge0.12 on Si(100)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138713 ◽

1995 ◽

Vol 53 ◽

pp. 468-469

Author(s):

N. David Theodore ◽

Donald Y.C Lie ◽

J. H. Song ◽

Peter Crozier

Keyword(s):

Integrated Circuits ◽

Heterojunction Bipolar Transistors ◽

Integrated Circuit ◽

High Speed ◽

Room Temperature ◽

Strain Relaxation ◽

Bipolar Transistors ◽

Sige Hbt ◽

Integrated Circuit Manufacturing ◽

Microstructural Behavior

SiGe is being extensively investigated for use in heterojunction bipolar-transistors (HBT) and high-speed integrated circuits. The material offers adjustable bandgaps, improved carrier mobilities over Si homostructures, and compatibility with Si-based integrated-circuit manufacturing. SiGe HBT performance can be improved by increasing the base-doping or by widening the base link-region by ion implantation. A problem that arises however is that implantation can enhance strain-relaxation of SiGe/Si.Furthermore, once misfit or threading dislocations result, the defects can give rise to recombination-generation in depletion regions of semiconductor devices. It is of relevance therefore to study the damage and anneal behavior of implanted SiGe layers. The present study investigates the microstructural behavior of phosphorus implanted pseudomorphic metastable Si0.88Ge0.12 films on silicon, exposed to various anneals.Metastable pseudomorphic Si0.88Ge0.12 films were grown ~265 nm thick on a silicon wafer by molecular-beam epitaxy. Pieces of this wafer were then implanted at room temperature with 100 keV phosphorus ions to a dose of 1.5×1015 cm-2.

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