I think i have problem

Posted by Yasri Yudhistira

I really hate to admit that probably my English deteriorates. That’s
why now i write this post in English against my intention to make this
blog purely in bahasa Indonesia.

Today i had series of meetings that require me to talk actively but
somehow I was stucked speechless.

It’s not that my English is perfect nor bad to start with. I had
talked in a few international seminars before so I guess it’s not that
bad, is it?

Anyway, I guess I can trace back on why this probably happens. First
of all, maybe because of this blog that push me to think in Bahasa
again.

Second maybe I talked in Bahasa much more often nowadays after I get
married. Not to blame my wife that she speaks Bahasa but it’s also
because my own wish to speak my mother tongue to my family. I don’t
want my family to forget where they belong to. I observed that some
indonesian family totally speak in English that they can’t speak
Bahasa anymore. I don’t want that to happen to my own family.

My bigger problem to keep my English is the fact that in the next
couple of weeks I’m relocating to Europe. And I got to learn a new
language to survive.

Oh life. So I guess i should start another blog in English, shouldn’t I?

Overlay

Posted by Yasri Yudhistira

Salah satu hal yang cukup rumit dalam proses litografi adalah overlay,
yaitu ukuran seberapa baik satu layer dicetak diatas layer yang lain.

Chip tersusun dari beberapa lapis material yang memiliki pola tertentu
dan saling terkait satu sama lain.

Analogi sederhananya seperti teknik sablon pada baju atau kartu ucapan berwarna.

Tukang sablon akan membuat beberapa master berdasarkan warna. Kemudian
master-master ini dicetak pada baju atau kartu ucapan secara berurutan
hingga semua warna pada desain tercetak.

Pada analogi tukang sablon, mereka harus memastikan bahwa cetakan
setiap master harus simetris tepat di atas cetakan sebelumnya.

Kembali pada proses litografi, ukuran seberapa baik suatu layer
dicetak di atas layer lain disebut overlay.

Chipmaker harus bisa mengontrol overlay hingga satu per 10 ribu
diameter rambut manusia.

Bagaimana caranya? Yaitu dengan optics. Maksudnya bukan sekedar
mikroskop, tapi juga memanfaatkan difraksi untuk membaca tanda
alignment pada wafer dan interferometer untuk mengatur posisi wafer di
bawah lensa.