Polycrystalline silicon doped films

To avoid catalytic interaction of the analyte with a heater made of noble metal, the films are frequently coated with a thin, chemically inert layer of SiO. Such passivation very often serves as a support for further functional layers in top-down microelectronic technologies. It should be noted that the passivation of electrode materials allows a reduction in requirements relating to their thermodynamic stability. In particular, the indicated approach is used in micro-hotplate fabrication. As a result most micro-hotplate designers consider polycrystalline silicon doped with boron or phosphorus impurities to be a very appropriate material for making heaters and temperature sensors because, with capsulation covering, it is stable up to 1,000 °C (Panchapakesan et al. 2001 Hwang... 

Polysilicon is a contraction of polycrystalline silicon, (in contrast with the single-crystal epitaxial silicon). Like epitaxial silicon, polysilicon is also used extensively in the fabrication of IC s and is deposited by CVD.f l it is doped in the same manner as epitaxial silicon. Some applications of poly silicon films are ... 

It has been suggested that when phosphorus-doped polycrystalline silicon is produced by LPCVD of SiH4-PH3 mixtures, gaseous SiH2 that reaches the surface becomes the dominant contributor to film formation383. It seems, however, that the quality of the films deposited by LPCVD from SilI4 increases if gas-phase decomposition, and hence SiH2 formation, decreases . 

Whether or not a chemical process step has been successful is difficult to measure, since there are few on-line measurable electrical properties. For example, film thickness and grain structure of polycrystalline silicon can be measured after a deposition step. However, their effect on device performance might not show up until subsequent doping or patterning steps fail. Similarly, it is possible to measure etch rates on-line by laser interferometry, but the etch profiles must be checked by electron microscopy. Unexpected mask undercutting or undiscovered etch residues can result in subsequent contact and device lifetime problems. 

DOPING EFFECT ON THE STRUCTURE OF POLYCRYSTALLINE SILICON FILMS... 

For high electric and thermal conductivity, metals such as gold (Au), copper (Cu), and aluminum (Al) are used widely. Magnetic metals such as nickel (Ni) and iron (Fe) are utilized to form magnetic actuators. Some metal thin films such as chromium (Cr) and titanium (Ti) are applied to enhance the adhesion of other metal thin films to a substrate. Doped polycrystalline silicon and metal silicides [12] have electric conductivities slightly inferior to metals but much better than insulators. They have also become integral materials for microelectronics. 

Integrated circuits (ICs) are comprised of layers of deposited thin films of metals and dielectrics which form device elements and metal contacts between the elements. The common methods of deposition are physical vapor deposition (PVD) and chemical vapor deposition (CVD). PVD is usually used to deposit metals like aluminum. CVD is often the process for growing oxides and polycrystalline silicon, which is doped to act as a metal electronically. 

Polysilicon - Polycrystalline silicon extensively used as conductor/gate materials in a highly doped state. Poly films are typically deposited using high-tem-perature CVD technology. 

This approach was validated by mapping an approximately 1 pm thick p-doped polycrystalline silicon film sandwiched on each side by a 1 pm thick film of silica. 

The specific application of a material generally determines the particular structure desired. For example, hydrogenated amorphous silicon is used for solar cells and some specialized electronic devices (10). Because of their higher carrier mobility (see Carrier Transport, Generation, and Recombination), single-crystalline elemental or compound semiconductors are used in the majority of electronic devices. Polycrystalline metal films and highly doped polycrystalline films of silicon are used for conductors and resistors in device applications. 

It is noted that the polishing of the polysilicon film will employ the well-known technology of polishing monocrystalline silicon substrates. This gives an opportunity to examine the effect of polycrystallinity and thus of grain boundaries and grain orientation in CMP of Si. Doped vs. undoped polysilicon will also shed... 

Boron-doped diamond (BDD) thin films were synthesized at CSEM (Neuchatel, Switzerland) by the hot filament chemical vapor deposition technique (HF CVD) on p-type, low-resistivity (l-3mQcm), single-crystal, silicon wafers (Siltronix). The temperature of the filament was between 2440 and 2560 °C and that of the substrate was monitored at 830 °C. The reactive gas was a mixture of 1% methane in hydrogen, containing trimethylboron as a boron source (1-3 ppm, with respect to H2). The reaction chamber was supplied with the gas mixture at a flow rate of 51 min giving a growth rate of 0.24 pm h for the diamond layer. The obtained diamond film has a thickness of about 1 pm ( 10%) and a resistivity of 15mQcm ( 30%). This HF CVD process produces columnar, random textured, polycrystalline films [9]. 

Recently, both polycrystalline and microcrystalline ( 200 A crystallite size) Si films have been investigated by ESR (Hasegawa ft a/., 1981b, 1983b). A dangling bond resonance in microcrystalline silicon films is observed at g = 2.0049. The spin density of this resonance is typically between 10 and 10 spins cm. In P-doped samples a conduction-electron spin-resonance signal is observed at = 1.997. 

Doped diamond is the alternative carbon material to glassy carbon for ozone generation [20,21], but the technology is much less developed. Boron-doped diamond is prepared by chemical vapor deposition and has been used as an anode when (i) deposited as a thin film on substrates such as silicon, titanium, or niobium or (ii) fabricated as a bulk plate - for example. Element Six supplies Diafilm EP as a free-standing polycrystalline plate capable of supporting current densities of >1 Acm [25]. Typically, the boron-doping concentration is 10 °-10 atoms cm when its resistivity is of the order of 0.05 cm. These boron-doped... 

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