摘要:

To obtain optimal results from plasma processing, the energy of ions incident on substrate wafers must be carefully controlled. Such control has been difficult to achieve, however, because no practical method exists for monitoring the energy distributions of ions at a wafer surface during processing. To solve this problem, we have developed a noninvasive, model‐based method for determining ion energy distributions (IEDs) that is suitable for use during actual processing in commercial plasma reactors. The method was validated by tests performed in argon and CF4discharges at 1.3–3.1 Pa (10–23 mTorr) in an inductively coupled, high‐density plasma reactor, with radio‐frequency (rf) substrate bias at frequencies of 0.1 MHz to 20 MHz. Plasma potential waveforms and sheath voltages obtained from the noninvasive rf technique agreed well with independent measurements made using a capacitive probe. Ion energy distributions from the rf technique were in good agreement with distributions measured by ion energy analyzers. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622471

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Lightpipe radiation thermometers (LPRTs) are used as temperature monitoring sensors in most rapid thermal processing (RTP) tools for semiconductor fabrication. These tools are used for dopant anneal, gate oxide formation, and other high temperature processing. In order to assure uniform wafer temperatures during processing these RTP tools generally have highly reflecting chamber walls to promote a uniform heat flux on the wafer. Therefore, only minimal disturbances in the chamber reflectivity are permitted for the sensors, and the small 2 mm diameter sapphire lightpipe is generally the temperature sensor of choice. This study was undertaken to measure and model the effect of LPRT proximity on the wafer temperature. Our experiments were performed in the NIST RTP test bed using a NIST thin‐film thermocouple (TFTC) calibration wafer. We measured the spectral radiance temperature with the center lightpipe and compared these with the TFTC junctions and with the three LPRTs at the mid‐radius of the wafer. We measured LPRT outputs from a position flush with the reflecting plate to within 2 mm of the stationary wafer under steady‐state conditions with wafer‐to‐cold plate separation distances of 6 mm, 10 mm and 12.5 mm. Depressions in the wafer temperature up to 25 °C were observed. A finite‐element radiation model of the wafer‐chamber‐lightpipe was developed to predict the temperature depression as a function of proximity distance and separation distance. The experimental results were compared with those from a model that accounts for lightpipe geometry and radiative properties, wafer emissivity and chamber cold plate reflectivity. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622472

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

New analytical techniques and applications are needed to address the challenges facing the semiconductor industry as transistor feature sizes continue to decrease beyond the 100 nm technology node. Several new applications of quadrupole ion trap (QIT) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry are presented, specifically applied to process tool effluent characterization. A QIT with atmospheric pressure transfer line and pneumatically driven valves is used to characterize a dielectric etch process, with response times comparable to extractive Fourier transform infrared (FTIR) spectroscopy. The QIT allows application of collision‐induced dissociation (CID) for structure elucidation, and is useful when high‐molecular weight metal organic precursors are used in processes that evolve byproducts that are ambiguous by gas‐phase infrared analysis. Similarly, a transportable FTICR with a fixed magnet and pulsed‐valve sample introduction allows matrix ion ejection to improve the sensitivity to analyte ions. The FTICR has also been evaluated for a low‐pressure chemical vapor deposition (LPCVD) process using a high‐molecular weight precursor. Byproducts are ambiguous in FTIR spectra, but the FTICR provided structural confirmation of the effluent species, and is a useful complement to FTIR. The FTICR was also used with FTIR to characterize process tool effluent emissions in a study using SF6and Ar to plasma etch a candidate metal oxide gate electrode material, RuO2. The results confirmed that no significant amount of RuO4, a toxic byproduct, were produced in this process. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622473

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

CMOS devices fabricated in a strained Si layer grown epitaxially on a strain‐relaxed SiGe virtual substrate exhibit enhanced carrier mobility compared to that of devices fabricated in bulk Si. We demonstrate that the thickness and strain state of the Si layer, and the alloy composition and strain state of the SiGe “virtual substrate” are critical parameters for process monitoring. The strengths and limitations of several characterization methods including x‐ray diffraction, Raman spectroscopy and spectroscopic ellipsometry for characterization of these layer structures are discussed. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622474

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The electron and hole mobility of Si complementary metal on oxide field effect transistors (CMOS) can be enhanced by introducing a biaxial tensile stress in the Si channel. This paper outlines several key analytical techniques needed to investigate such layers. Raman scattering is used to measure the strain in the Si channel as well as to map the spatial distribution of strain in Si at a lateral resolution better than 0.5 &mgr;m. Atomic force microscopy (AFM) is used to measure the surface roughness. Transmission electron microscopy (TEM) is used to reveal dislocations in the structure, the nature of the dislocations and the propagation of the dislocations. Secondary ion mass spectrometry (SIMS) is used to monitor the Ge content profile in the structure and the thickness of each layer. In the long term, inline nondestructive techniques are desired for epi‐monitoring in manufacturing. Two techniques, spectroscopic ellipsometry (SE) and x‐ray reflectivity (XRR), have shown promise at this stage. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622475

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The SiGe:C hetero‐structure bipolar transistor (HBT) has turned into a key technology for wireless communication. This paper describes various critical analytical techniques to bring up and maintain the SiGe:C epi‐process. Two types of analysis are critical, (1) routine monitoring SiGe base and Si cap thickness, doping dose, Ge composition profile, and their uniformity across the wafer; and (2) root‐cause analysis on problems due to non‐optimized process and variation in process conditions. A transmission electron microscopy (TEM) technique has been developed allowing a thickness measurement with a reproducibility better than 3 Å. Charge‐compensated low‐energy secondary ion mass spectrometry (SIMS) using optical conductivity enhancement (OCE) allows a Ge composition measurement to a required precision of 0.5 at. &percent;. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622476

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Graded Si1−xGexstructures have been measured with good accuracy, stability and tool‐tool matching by utilizing different measurement methods in one system (Opti‐Probe®). The measurement methods utilized are (i) laser reflectivity versus angle for S and P polarization (BPR®), (ii) visible‐DUV reflectometry (BB), and (iii) spectroscopic ellipsometry (SE). An alloy dispersion model, along with a multi‐layer linear graded‐material model, were used to process the data and extract the thickness of the cap‐Si, graded and spacer Si1−xGexlayers, as well as the Ge&percent;, simultaneously. The results were found to be in agreement with subsequent SIMS analysis to within 50Å for all layers and 0.5&percent; atomic Ge&percent;. Stability and matching results for thickness were <13Å (3&sgr;) for all layers, and for the Ge&percent; the stability was <0.25–0.6&percent; (3&sgr;). © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622477

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Bulk SiGe wafers cut from single‐crystal boules were evaluated with the electron probe microanalyzer (EPMA) for micro‐ and macroheterogeneity for use as primary standards for future characterization of SiGe thin films on Si that are needed by the microelectronics industry as reference standards. Specimens with nominal compositions of 14 at. &percent;, 6.5 at. &percent;, and 3.5 at. &percent; Ge were rigorously tested with wavelength dispersive spectrometers (WDS) using multiple point, multiple sample, and duplicate data acquisitions. The SiGe14 is a good bulk reference material for evaluation of SiGe thin films. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622478

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

As ULSI technology continues to advance, semiconductor manufacturers are facing new contamination control and monitoring challenges, including airborne molecular contamination (AMC). AMC is being recognized as one of the yield limiting factors in newer generation microelectronics fabrication processes. A major AMC source, materials’ outgassing can introduce a variety of organic contaminants into semiconductor fabs, impacting many processes. This paper provides a brief overview of typical organic outgassing contaminants, their sources, process impacts and analytical techniques used to detect these species. In addition, outgassing study results for polycyclodimethylsiloxanes and several other contaminants using thermal desorption‐gas chromatography‐mass spectrometry (TD‐GC‐MS) analysis are employed to demonstrate the relationships among (1) outgassing level and outgassing time (linear), (2) outgassing quantity and the inverse of outgassing temperature (logarithmic), and (3) outgassing quantity and material surface area (linear). A new method, based on gas diffusion conductivity detection, for ammonia and volatile amines’ outgassing analysis is also presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622479

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Direct to Digital Holography (DDH) has been developed as a semiconductor wafer inspection tool and in particular as a tool for seeing defects in high aspect ratio (HAR) structures on semiconductor wafers and also for seeing partial‐height defects. While the tool works very well for general wafer inspection, it has unusual capabilities for high aspect ratio inspection (HARI) and for detecting thin residual film defects (partial height defects). Inspection of HAR structures is rated as one of the highest unmet priorities of the member companies of International SEMATECH, and finding residual thin film defects (in some cases called “stringers”) is also a very difficult challenge. The capabilities that make DDH unusually sensitive include: 1) the capture of the whole wave—both the classical amplitude captured by traditional optical systems, and the phase of the wave, with phase potentially measured to ∼1/1000’th of a wavelength or ∼2 to 3 Angstroms for a deep ultra‐violet (DUV) laser; 2) heterodyne detection—this allows it to capture very low signal levels; and 3) a head‐on geometry using a collimated laser beam that allows best penetration of HAR structures. The basic features and methods of this patented technology are presented, along with simple calculations of signal strength and expected noise levels for various circumstances. Full‐wave numerical calculations of electromagnetic field penetration into HAR contacts and experimental results from various wafer types and structures are also presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1622480

出版商:AIP    

年代:1903

数据来源: AIP