The present invention relates to manufacturing converters of heat to electric energy and, more specifically, to a method of manufacturing a film thermopile.
Known at present is a method of manufacturing a film thermopile, whereby strips of a thermoelectric semiconductor material of one type of conduction, e.g. a p-type (p-arms) are deposited through an aligned mask on a substrate of an insulation material. After depositing the p-type material, in order to improve its electrical and physical properties, it is common to effect heating in an inert medium or in a vacuum. Then the aligned mask is changed and strips of a thermoelectric semiconductor material of an n-type (n-arms) are deposited and refined in an inert medium or in a vacuum. Usually the chemical composition of the p-arm material differs from that of the n-arm material, therefore the refinement conditions for the p-arm material differs from those of the n-arm material, which necessitates two separate steps of heating for the p-arms and the n-arms.
Having deposited the p- and n-arms, switching buses are deposited for electrical connection of the p- and n-arms.
This method of manufacturing a film thermopile brings about the necessity of aligning masks to deposit the p- and n-arms which greatly limits the minimum width of the arms.
Also, the deposited arms of one type should be protected against damage by aligned masks while depositing the arms of opposite conduction. The arms of one type being deposited, an operation of changing the masks for depositing the arms of another type is necessary, too. This operation considerably lengthens the technological process of manufacturing a film thermopile. Moreover, the changing of the masks may cause damage to the active layer of the p- or n-arms.
The known method makes it impossible to clean the substrate surface by heat treatment as the substrate heating may result in re-evaporation of the p-arms already deposited. It is possible to overcome this drawback by depositing arms of both types simultaneously, e.g. evaporating the p-arms from one crucible and the n-arms from another crucible, however films of uniform thickness and composition would not be obtained.