pad with epoxy material, and its parts are bonded to the leads of the package with
tiny gold or aluminum wires before being placed into a molding press that encapsulates the setup in plastic [20].
The semiconductor is further cured, excess material is removed through chemical
or mechanical deflash process, and finally, the leads are trimmed and formed. Many
of the semiconductor manufacturing companies in the USA do not dice finished their
wafers but export them to other facilities overseas where dicing and assembly
process relatively cost less.
Gallium Arsenide and Gallium Phosphide Wafers
Often times the starting material for these product types of semiconductor is the
wafer which is usually procured from crystal growers. The procured wafers are first
placed in a furnace to grow a silicon nitride layer on it. Following this, the wafer is
coated with a layer of photoresist and then exposed to ultraviolet light through glass
photomasks that allow the light to strike only selected areas. It is, however, developed with a xylene-based developer. The resist is then stripped off after the wafer has
been chemically etched and rinsed with deionized water. Thereafter, its surface is
doped with a selected dopant, covered with metal oxide and photoresist. After this, it
is masked, chemically etched with cyanide-containing chemical, and then rinsed in
deionized water. During the lapping process, the desired thickness is achieved, and
the pack is further sputtered with a layer of metal, usually gold, to provide contacts
for conductivity before the finishing, testing, and assembly. Semiconductors of this
type are predominantly used for the production of light-emitting diodes (LEDs).
Silicon and Germanium Semiconductors
The silicon and germanium semiconductors are discrete devices of small semiconductors of pure crystal placed between two and three contacts. The crystal materials
used for the production of these product types of semiconductor are first cleaned in
acid (or alkali) solution and thoroughly rinsed in deionized water before being
coated with a layer of photoresist. As in the production processes above, the wafer
is exposed chemically to hydrofluoric acid solution, and thereafter, the wafer is
rinsed, dried and doped with boron, gold, or phosphorus in diffusion furnace. Its
finishing involves dicing, placement between contacts, and sealing in rubber glass,
plastics, or ceramic; wires are attached before testing certification for use. They are
mostly used in transistors and diodes employed in less sophisticated equipment
designs as well as in high-power switching and amplification.
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O. S. Amuda et al.
tiny gold or aluminum wires before being placed into a molding press that encapsulates the setup in plastic [20].
The semiconductor is further cured, excess material is removed through chemical
or mechanical deflash process, and finally, the leads are trimmed and formed. Many
of the semiconductor manufacturing companies in the USA do not dice finished their
wafers but export them to other facilities overseas where dicing and assembly
process relatively cost less.
Gallium Arsenide and Gallium Phosphide Wafers
Often times the starting material for these product types of semiconductor is the
wafer which is usually procured from crystal growers. The procured wafers are first
placed in a furnace to grow a silicon nitride layer on it. Following this, the wafer is
coated with a layer of photoresist and then exposed to ultraviolet light through glass
photomasks that allow the light to strike only selected areas. It is, however, developed with a xylene-based developer. The resist is then stripped off after the wafer has
been chemically etched and rinsed with deionized water. Thereafter, its surface is
doped with a selected dopant, covered with metal oxide and photoresist. After this, it
is masked, chemically etched with cyanide-containing chemical, and then rinsed in
deionized water. During the lapping process, the desired thickness is achieved, and
the pack is further sputtered with a layer of metal, usually gold, to provide contacts
for conductivity before the finishing, testing, and assembly. Semiconductors of this
type are predominantly used for the production of light-emitting diodes (LEDs).
Silicon and Germanium Semiconductors
The silicon and germanium semiconductors are discrete devices of small semiconductors of pure crystal placed between two and three contacts. The crystal materials
used for the production of these product types of semiconductor are first cleaned in
acid (or alkali) solution and thoroughly rinsed in deionized water before being
coated with a layer of photoresist. As in the production processes above, the wafer
is exposed chemically to hydrofluoric acid solution, and thereafter, the wafer is
rinsed, dried and doped with boron, gold, or phosphorus in diffusion furnace. Its
finishing involves dicing, placement between contacts, and sealing in rubber glass,
plastics, or ceramic; wires are attached before testing certification for use. They are
mostly used in transistors and diodes employed in less sophisticated equipment
designs as well as in high-power switching and amplification.
156
O. S. Amuda et al.