Convergent beam electron diffraction measurements of relaxation in strained silicon using higher order Laue zone line splitting

Diercks, David R.; Kaufman, Michael J.; Needleman, A.

doi:10.1063/1.3093693

Cited by 4 publications

(7 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2). HOLZ line splitting in CBED patterns between 100 and 500 nm below the base of gate oxide was observed in this specimen and is indicative of stress relaxation (Diercks et al, 2009a). This suggests that the GPA reference point (∼230 nm below the gate oxide) may not be quite at zero strain.…”

mentioning

confidence: 82%

Comparison of convergent beam electron diffraction and geometric phase analysis for strain measurement in a strained silicon device

Diercks¹,

Lian²,

Chung³

et al. 2011

Journal of Microscopy

View full text Add to dashboard Cite

Key words. Convergent beam electron diffraction (CBED), geometric phase analysis (GPA), high-angle annular-dark-field scanning transmission electron microscopy (HAADF STEM), local strain measurement. SummaryConvergent beam electron diffraction and geometric phase analysis were used to measure strain in the gate channel of a p-type strained silicon metal-oxide-semiconductor field-effect transistor. These measurements were made on exactly the same transmission electron microscopy specimen allowing for direct comparison of the relative advantages of each technique. The trends in the strain values show good agreement in both the [110] and [001] directions, but the absolute strain values are offset from each other. This difference in the absolute strain measured using the two techniques is attributed to the way the reference strain is defined for each.Because strained silicon is being used on a highly localized scale to enhance the electrical performance of complementary metal-oxide-semiconductor (CMOS) devices (Chidambaram et al., 2004;Thompson et al., 2004), techniques for the quantitative measurement of elastic strain with high spatial resolution are increasingly necessary. Although convergent beam electron diffraction (CBED) and geometric phase analysis (GPA) have been used previously by several groups for these types of measurements (Toda et al., 2001;Hÿtch et al., 2003;Benedetti et al., 2004;Toh et al., 2005;Chung et al., 2008;Hüe et al., 2008), there have been no reports directly comparing the strain measurements from the two techniques for the same device structure. Because there are relative advantages and limitations of these techniques for strain measurement, a direct comparison of these two techniques should provide a better understanding of these. In CBED, a small, convergent probe is used to produce diffraction from both the zero-order and higher-order Laue zones (ZOLZ and HOLZ, respectively). The HOLZ diffraction appears as pairs of lines in the diffraction patterns -rings of excess lines diffracted to a relatively large angle and corresponding deficit lines in the central disk. Because these lines occur due to Bragg diffraction at relatively large angles, their positions are very sensitive to small changes in the crystal lattice. The sensitivity of lattice measurements using this technique can be on the order of 10 −4 . (Twigg et al., 1987;Kramer & Mayer, 1999) However, most silicon-based devices are oriented along 110 directions, and CBED patterns along this direction do not produce HOLZ lines under typically utilized CBED-operating conditions due to the large spacing between planes in the reciprocal lattice along this direction. Therefore, measurements using this technique are performed by tilting away from the 110 axis, typically along the 004 Kikuchi band, resulting in a loss of lateral resolution. This is particularly important as the scale of microelectronic devices continues to decrease. The degree of resolution loss depends on the angle of tilt from the [110] direction, so efforts have been ...

show abstract

mentioning

confidence: 82%

Comparison of convergent beam electron diffraction and geometric phase analysis for strain measurement in a strained silicon device

Diercks¹,

Lian²,

Chung³

et al. 2011

Journal of Microscopy

View full text Add to dashboard Cite

show abstract

“…Care was made to stay centred between the SiGe stressors for collection of the CBED patterns because HOLZ line splitting indicative of non‐uniform strain fields was observed in patterns from areas close to the stressors. It is also worth noting that HOLZ line splitting indicative of rotational relaxation was observed at distances 150–400 nm below the gate (Diercks et al , 2009). The sample thickness was measured as 323 nm using Kossel‐Möllenstedt fringes.…”

Section: Methodsmentioning

confidence: 99%

“…Also, there is a strain component due to relaxation normal to thinning direction, i.e. along the [110] (Diercks et al , 2009). To reduce the number of variables, it was assumed that a = b and α=β= 90° because, from symmetry, the compressive force from each side should be equal in the centre of the gate channel and the relaxation along the [110] direction would be the same on both sides of the specimen.…”

Section: Defining Variablesmentioning

confidence: 99%

“…Others have similarly seen that after a fitting algorithm determined a satisfactory solution, further iterations produced different, equally good solutions (Wittmann et al , 2000). Therefore, in this research, the relaxation in the [110] direction was calculated to be 0.10% using the method shown previously (Diercks et al , 2009). This left only two independent variables, from which a unique solution for each pattern was determined using a chi‐squared minimization (Zuo, 1992).…”

Section: Defining Variablesmentioning

confidence: 99%

See 1 more Smart Citation

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

Diercks

Kaufman

Irwin

et al. 2010

Journal of Microscopy

View full text Add to dashboard Cite

SummaryConvergent beam electron diffraction patterns of silicon from the gate channel region of a complementary metal-oxidesemiconductor transistor with recessed Si .82 Ge .18 stressors were analysed using three zone axes: <230>, <340> and <670>. Values measured using these axes were compared with each other with regards to strain along the [110] and the [001] directions. It was demonstrated that strain measurements made using all three axes showed reasonable agreement with each other: an increase in the [110] compressive strain and a switch from compressive to tensile strain in the [001] with decreasing distance below the gate. It was also observed that the strain calculations using the <230> axis had the lowest uncertainty whereas the <670> axis allowed for measurements closest to the gate due to the improved lateral resolution at that tilt angle.

show abstract

“…This technique is used in the works in Refs. [48][49][50][51][52][53][54][55] to study strain in MOSFETs. CBED uses a converging electron beam with a large angle of convergence to generate enlarged diffraction spots in the form of disks.…”

Section: Convergent-beam Electron Diffraction (Cbed)mentioning

confidence: 99%

UV Raman studies of channel stress in transistors with embedded SiGe source and drain

Wong¹

View full text Add to dashboard Cite

engineering technique, SiGe, which is epitaxially grown in the source and drain regions, acts as a stressor to induce a compressive strain in the channel. By varying the Ge concentration, it is possible to increase or decrease the amount of strain. Ever since the first report of this strain technology appeared in the International Electron Devices Meeting in 2002 [3], it has rapidly gained popularity and has become the main method for inducing compressive strain in p-type MOSFETs in production nowadays. 1.2 Overview of this thesis We begin with a literature review in Chapter 2. This chapter is divided into two main sections. The first section briefly reviews the field of MOSFETs with strained silicon channels. This section includes a description of the main physical mechanisms behind the improvement in carrier mobility when silicon is appropriately strained. It also provides information on the methods commonly used to strain the transistor channels. This section then moves on to describe the available methods that are used to quantify channel strain. Both simulation and experimental methods will be covered. A discussion of the strengths and limitations of current experimental methods, as well as the lack in studies in certain areas is then given. The second section of this chapter reviews the theory underlying the Raman scattering of semiconductors. Also included is the theory addressing the change in the Raman characteristics of silicon when a uniaxial stress is applied to it. Next, the materials, instrumentation, and methods used for the work in this thesis are given in Chapter 3. The process flow for the devices used is briefly described under the Materials section. For the Instrumentation and Methods section, details of the hardware and operation of our Raman spectroscopy system are provided. Relevant concepts such as spatial and spectral resolution are explained. Also described in this section are the finite-ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library CHAPTER 1: INTRODUCTION 3 difference time-domain (FDTD) method and the software program used for such work in the thesis. Chapters 4 to 6 cover the main projects undertaken for this thesis. Chapter 4 lays the foundation that Chapters 5 and 6 build upon. The sample preparation method, approach for channel stress measurements, and data analysis and interpretation are given in Chapter 4. Chapter 5 extends the research to study the effect of implantation and annealing on the channel stress. Chapter 6 includes FDTD simulations to provide insight into the distribution of the Raman excitation light in the structures studied in Chapters 4 and 5. Implications of using Raman excitation light of different polarizations are discussed. Chapter 7 then follows. This brief chapter contains some results of near-field Raman mapping for high spatial resolution work. Finally, Chapter 8 highlights the main conclusions of the work in this thesis and provides suggestions for further work. Note: Unless otherwise ...

show abstract

Convergent beam electron diffraction measurements of relaxation in strained silicon using higher order Laue zone line splitting

Cited by 4 publications

References 16 publications

Comparison of convergent beam electron diffraction and geometric phase analysis for strain measurement in a strained silicon device

Comparison of convergent beam electron diffraction and geometric phase analysis for strain measurement in a strained silicon device

Using a <670> zone axis for convergent beam electron diffraction measurements of lattice strain in strained silicon

UV Raman studies of channel stress in transistors with embedded SiGe source and drain

Contact Info

Product

Resources

About