MAKING A TRANSISTOR
1 FIRST MASKING
The silicon base is first coated with silicon dioxide, which does not conduct electricity, and then with a substance called photoresist. Shining ultraviolet light through a patterned mask hardens the photoresist. The unexposed parts remain soft.
2 FIRST ETCHING
A solvent dissolves away the soft unexposed layer of photoresist, revealing a part of the silicon dioxide. This is then chemically etched to reduce its thickness. The hardened photoresist is then dissolved to leave a ridge of dioxide.
3 SECOND MASKING
Layers of polysilicon, which conducts electricity, and photoresist are applied, and then a second masking operation is carried out.
4 SECOND ETCHING
The unexposed photoresist is dissolved, and then an etching treatment removes the polysilicon and silicon dioxide beneath it. This reveals two strips of p-type silicon.
The hard photoresist is removed. The layers now undergo an operation called doping which transforms the newly revealed strips of p-type silicon into n-type silicon.
6 THIRD MASKING AND ETCHING
Layers of silicon dioxide and photoresist are added. Masking and etching creates holes through to the doped silicon and central polysilicon strip.
7 COMPLETING THE TRANSISTOR
The photoresist is dissolved, and a final masking stage adds three strips of aluminium. These make electrical connections through the holes and complete the transistor.
In this transistor, known as an MOS type, a positive charge fed to the gate attracts electrons in the p-type silicon base. Current flows between the source and the drain, thereby switching the transistor on. A negative charge at the gate repels electrons and turns the current off.
|Coming from the Mill|
|Artist||Laurence Stephen Lowry|
|Medium||oil on canvas|
|Dimensions||42 cm × 52 cm (17 in × 20 in)|
|Location||The Lowry, Salford|
Coming from the Mill is a painting by British painter Laurence Stephen Lowry from 1930.
Laurence Stephen Lowry (1887–1976) often painted his surroundings in Pendlebury, Lancashire in the United Kingdom, where he lived and worked for more than 40 years. His fame lies in images from the industrial districts in the northwest of England from the mid-1900s. He developed a painting style of cityscapes with people, often described as "matchstick men". He also painted mysterious unpopulated landscapes and discordant portraits.
He is sometimes referred to as naïvist and often got to hear, to his annoyance, that he was a self-taught amateur "Sunday painter".
On the way home from the factory shows workers going home from a factory after the end of their shift. It is based on a previous pastel drawing by the same artist: Coming from the Mill from about 1917-18. Lowry himself considered the oil painting that "his most characteristic mill scene". It does not show a real factory, but the environment is composed of individual buildings with real details from his imagination.
On the way home from the factory was bought by the artist in 1940 and is now at The Lowry, a theater and art gallery complex that opened in 2000 at Pier 8, Salford Quays in Salford in Greater Manchester in the UK, which is named for Lowry.
- This article incorporates information from the equivalent article on the Swedish Wikipedia.