Temperatures deposition

Parikh A N, Allara D L, Azouz I B and Rondelez F 1994 An intrinsic reiationship between moiecuiar-structure in seif-assembied / -aikyisiioxane monoiayers and deposition temperature J. Phys. Chem. 98 7577-90... 

An important further constraint is the fact that economic considerations ia the constmction of deposition equipment normally lead to a preference for an ambient temperature deposition chamber. Control of deposition temperature is possible, but it adds both equipment expense and operational complexity. 

Plasma-deposited siUcon nitride contains large amounts of hydrogen, typically in the range of 20—25 atomic % H, and has polymer-like properties. The electrical resistivity of the film depends on the deposition temperature, the film stoichiometry, and the amounts of hydrogen and oxygen in the film. 

The stmcture of the polysihcon depends on the dopants, impurities, deposition temperature, and post-deposition heat annealing. Deposition at less than 575°C produces an amorphous stmcture deposition higher than 625°C results in a polycrystalline, columnar stmcture. Heating after deposition induces crystallization and grain growth. Deposition between 600 and 650°C yields a columnar stmcture having reasonable grain size and (llO)-preferred orientation. 

The selection of a particular deposition process depends on the material to be deposited and its availabiUty rate of deposition limitations imposed by the substrate, eg, maximum deposition temperature adhesion of deposit to substrate throwing power apparatus required cost and ecological considerations. Criteria for CVD, electro deposition, and thermal spraying are given in Table 2 (13). 

The optoelectronic properties of the i -Si H films depend on many deposition parameters such as the pressure of the gas, flow rate, substrate temperature, power dissipation in the plasma, excitation frequency, anode—cathode distance, gas composition, and electrode configuration. Deposition conditions that are generally employed to produce device-quahty hydrogenated amorphous Si (i -SiH) are as follows gas composition = 100% SiH flow rate is high, --- dO cm pressure is low, 26—80 Pa (200—600 mtorr) deposition temperature = 250° C radio-frequency power is low, <25 mW/cm and the anode—cathode distance is 1-4 cm. 

The largest quantity of commercial pyrolytic graphite is produced in large, inductively heated furnaces in which natural gas at low pressure is used as the source of carbon. Deposition temperatures usually range from 1800 to 2000°C on a deposition substrate of fine-grain graphite. 

Figure 6-14. Average domain size vs. inverse deposition temperature Tor different film thicknesses. Error bars represent the mean absolute error and straight lines the best lit for each film thickness. Doited line is the locus of the transition from grains to lamellae. Data for 50-nm films are estimated from the correlation length of the topography fluctuations. Adapted from Ref. [501.

Figure 6-13. OrienUliunal order parameter vs deposition temperature. Cireles and squares are grains and lamellae, respectively. Straight lines represent best-lit for the lamellae data and mean value of the grain data, respectively. Adapted from Ref. 49. ...

Metallo-organic CVD (MOCVD) and plasma CVD are developing rapidly, not only in the semiconductor-microelectronic area but also in hard coatingsfor erosion andwearapplicationssincethelower deposition temperature now permits the use of a broader spectrum of substrates. Special emphasis hasbeen given to these two areas in this second edition of the CVD Handbook (see Ch. 4 and 5). 

In Fig. 2.2, the critical deposition temperature of NbCl5 as a function of its initial pressure, is shown from experimental data from Blocher and the author. There are two temperature-pressure regions, which are separated by a straight line. The metal is deposited only in the region below the line. Above, there is no deposition. The line is a least-square fit of the data. Its position was confirmed using the SOLGASMIX computer program. 

In this table, the free energy of formation, AGf of the chloride of these metals is listed for four different temperatures. As can be seen, the values are more negative than that of hydrogen chloride. These metals can be used to reduce the halides of titanium, zirconium, or hafnium, whereas hydrogen, as mentioned above, cannot do so readily. In order to be useful in CVD, the by-product chloride must be volatile at the deposition temperature. This may rule out the use of sodium or potassium, which evaporate above 1400°C. 

Thermal CVD, reviewed above, relies on thermal energy to activate the reaction, and deposition temperatures are usually high. In plasma CVD, also known as plasma-enhanced CVD (PECV) or plasma-assisted CVD (PACVD), the reaction is activated by a plasma and the deposition temperature is substantially lower. Plasma CVD combines a chemical and a physical process and may be said to bridge the gap between CVD andPVD. In this respect, itis similar to PVD processes operating in a chemical environment, such as reactive sputtering (see Appendix). 

The decomposition yields the metal and hydrocarbons. The TMA reaction has a tendency to leave carbon incorporated in the metal. Both TEA and TIBA have very low vapor pressure at room temperature and are consequently difficult to use. DMAH is generally the preferred precursor. Deposition temperature range is 200-300°C and pressure up to 1 atm (Note these alkyls are pyrophoric.)... 

The deposition temperature range is 280-3 05°C and the pressure is <1 Torr. This reaction has a tendency to incorporate carbon in the deposit. 

Reaction temperature ranges from 300 to 700°C and pressure from about 1 Torr to 1 atm. The reaction is carried out in a hydrogen atmosphere to reduce the possibility of carbon contamination. A deposition temperature > 450°C is required to eliminate the incorporation of C and O2 in the deposit.P P ]... 

Deposition temperature range i s 500-900°C with best deposits obtained at 700°C. At the low end of the temperature range, fluoride compounds remain incorporated in the deposit. Pressure is usually <20... 

Deposition temperature rangeis 1000-1250°C and best deposits are obtained at low pressure (< 20 T orr). This reaction usually gives a more ductileandpurermaterialthandoesReaction(l)althoughhighertempera-ture is necessary. The chloride is generally prepared in situ by direct chlorination by heating the metal at 500-600°C (see Ch. 4).Pi... 

Deposition temperature range is 400-600°C at a pressure of 200 Torr. Rhenium carbonyl is a solid at room temperature and must be vaporized at a temperature > 117°C. It decomposes at 250°C. This reach on is used for the coating of spheres in a fluidized bed. 

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