Silver (Ag) Pellets Evaporation Materials

Silver (Ag) Pellets Overview

We sell these pellets and pieces by unit weight for evaporation use in deposition processes. These approximate materials prices are published to provide budgetary guidelines. Actual prices can vary and may be higher or lower, as determined by availability and market fluctuations. To speak to someone directly about current pricing, please click here .

Silver (Ag) General Information

Silver is a soft, lustrous element that belongs to the transition group of metals on the periodic table. It has a melting point of 962°C, a density of 10.5 g/cc, and vapor pressure of 10^-4 Torr at 1,105°C. Silver has been used since ancient times in countless products. It is ductile, malleable, and the most electrically conductive of all metals. It is considered a precious metal and can be found in jewelry, solders, paints, and mirrors. It is evaporated under vacuum for the production of semiconductors, sensors, fuel cells, and optical coatings.

Silver (Ag) Specifications

**** Suggestion based on previous experience but could vary by process. Contact local KJLC Sales Manager for further information

Z-Factors

Empirical Determination of Z-Factor

Unfortunately, Z Factor and Shear Modulus are not readily available for many materials. In this case, the Z-Factor can also be determined empirically using the following method:

• Deposit material until Crystal Life is near 50%, or near the end of life, whichever is sooner.
• Place a new substrate adjacent to the used quartz sensor.
• Set QCM Density to the calibrated value; Tooling to 100%
• Zero thickness
• Deposit approximately 1000 to 5000 A of material on the substrate.
• Use a profilometer or interferometer to measure the actual substrate film thickness.
• Adjust the Z Factor of the instrument until the correct thickness reading is shown.

Another alternative is to change crystals frequently and ignore the error. The graph below shows the % Error in Rate/Thickness from using the wrong Z Factor. For a crystal with 90% life, the error is negligible for even large errors in the programmed versus actual Z Factor.

Thermal Evaporation of Silver (Ag)

We recommend thermally evaporating silver with a tungsten boat or a shielded tantalum or tungsten basket crucible heater with an aluminum oxide crucible. With an evaporation temperature of 1,100°C and a base pressure of 10^-6 Torr or lower, we anticipate a deposition rate of 1-5 angstroms per second. If using a KJLC^® system, we recommend our EVS8B005W which is a notched, dimple-style tungsten boat.

If using a KJLC^® system, we recommend our EVCH1 or EVCH10 tantalum heaters with an EVC9AO alumina crucible for the crucible heater/crucible method. Great care must be taken when installing the heater to prevent the outer shields from becoming warped which can cause a short in the heater, causing the welded joints to fail. The heater should be centered between the contacts and the outer shielding must be clear of the leads. Crucibles should be stored in a cool, dry place and always handled with gloves or forceps.

Correct - Crucible heater centered, outer shielding clear of leads

Incorrect - Crucible heater off-center, shielding in contact with leads/inner shielding

E-beam Evaporation of Silver (Ag)

Silver is rated excellent for e-beam evaporation. We recommend using a FABMATE^®, molybdenum, tungsten, or tantalum crucible liner.

We also recommend sweeping the e-beam and ramping power to fully melt the material. Once melted, a focused e-beam can be used to deposit films. With an evaporation temperature of 1,100°C and a base pressure of 10^-6 Torr or lower, we anticipate a deposition rate of 1-5 angstroms per second. It is important to note that carbon contamination from the crucible liner may occur. One way to reduce this is to decrease the power and the deposition rate.

A key process note is to consider the fill volume of the crucible liner. We find that the melt level of a material in the crucible directly affects the success of the crucible liner. Overfilling the crucible will cause the material to spill over and create an electrical short between the liner and the hearth. The outcome is cracking in the crucible liner. This is the most common cause of crucible liner failure. Placing too little material in the liner or evaporating too much material before refilling can be detrimental to the process as well. When the melt level is below 30%, the e-beam is likely to strike the bottom or walls of the crucible which immediately results in breakage. Our recommendation is to fill the crucible between 2/3 and 80% full to prevent these difficulties.

Crucible liners should be stored in a cool, dry place and always handled with gloves or forceps.