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Enhanced E-Beam Evaporation of Tin

IP.com Disclosure Number: IPCOM000046390D
Original Publication Date: 1983-Jul-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Marcotte, VC: AUTHOR [+3]

Abstract

During E-beam evaporation of tin, molten tin splashes under high power and spills onto cooling hearth, cooling down crucible. The objective here is to evaporate tin at a high angstrom per second rate. With the crucible in contact with the copper cooling hearth a much higher rate can be obtained. However, spitting of tin occurs with splash out and shorting of the crucible to the cooling hearth. Spacers between the crucible and the cooling hearth were tried so as to reduce the cooling of the tin. Copper, stainless steel, and molybdenum were tried. Higher evaporation rates could be obtained with both copper and stainless steel, but they eventually reacted and stuck to the bottom of the crucible. Molybdenum works very well and has not stuck to the bottom of the crucible to date. The general design concept is shown in Fig. l.

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Enhanced E-Beam Evaporation of Tin

During E-beam evaporation of tin, molten tin splashes under high power and spills onto cooling hearth, cooling down crucible. The objective here is to evaporate tin at a high angstrom per second rate. With the crucible in contact with the copper cooling hearth a much higher rate can be obtained. However, spitting of tin occurs with splash out and shorting of the crucible to the cooling hearth. Spacers between the crucible and the cooling hearth were tried so as to reduce the cooling of the tin. Copper, stainless steel, and molybdenum were tried. Higher evaporation rates could be obtained with both copper and stainless steel, but they eventually reacted and stuck to the bottom of the crucible. Molybdenum works very well and has not stuck to the bottom of the crucible to date. The general design concept is shown in Fig. l. Other materials which could reduce heat transfer are Al2O3, ZrO2 or other oxides or metals with high melting points. Fig. 2 shows a copper spacer beneath a single crucible. Copper was not satisfactory for these purposes, because of the higher power used to evaporate tin. Also, the design of the lead hearth (Fig. 2) and tin hearth (Fig. 3) are very different. The design shown in Fig. 2 can evaporate lead and tin from one crucible, whereas the design shown in Fig. 3 co-evaporates lead from one crucible and tin from another crucible.

The spacer reduces the heat flow from the crucible and results in a more stable me...