Hi,
I am just wondering how people define primary flat and secondary flat. I know in and Silicon Wafer, there are both p and n type.
90° angle between flats indicates it is a p type silicon wafer
180° angle between flats indicates it is a n type silicon wafer
Absence of secondary flat indicates it is a p type silicon wafer
45° angle between flats indicates it is a n type silicon wafer
However, my question is why would people define in this way? Is that simply byAsk convention or there is a reason to do so?
Chenjin,
These flats are introduced to identify the orientation of the wafer surface and the doping type. Since both are binary numbers that has only two possible orientations and two possible doping, one needs two logic symbols to identify the possible combinations as you described in your question. These information is important and if they are lost one has to makes tests to get these information which leads to extra cost and time.
The flats are visual code to identify the wafers. One may use an other method to store this information about the wafers.
For more information please see the link: http://www.tf.uni-kiel.de/matwis/amat/elmat_en/kap_5/illustr/i5_2_4.html
Best wishes
Hi Zekry,
Totally understand the reason to do so. However, I want to know why people define in this way, for example, that absence of secondary flat indicates a p type , rather than, say, n type ? Is there a particular reason to do so, or it is just by convention?
Thanks a lot
Chenjin
Hi Zekry,
I would think of one reason is due to the crystallographic direction that makes cleave easier.
Regards
Chenjin
Dear Chenjin,
You speak of the direction of major flat. It is 110 direction which is a cleavage direction making the formation of the flat easier. This is the selection of the direction of the primary flat no the the selected code. This is included in the reference which i included in my first post.
Best wishes
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