ICs are fabricated by a series of deposition of layers of material and etching. Bonding wires are only used to connect the die to the IC pins.

http://www.circuitstoday.com/nmos-ic-fabrication-process

http://www.chm.bris.ac.uk/~paulmay/misc/msc/msc1.htm

 

...I think I should also rephrase the query about the frequency rating, MHz, GHz, etc. In my practical life I have never seen a square wave. What I understand so far is that the frequency rating only tell the maximum rate at which transistors in the chip can work. If the frequency is 20 Hz then that would mean that a transistor could turn on and off 20 times a second. And if we try to run transistor at a frequency larger than the specified then it would get damaged. Do I make any sense? I don't know any exact search terms to search this topic on UTube, could you please help?...

For some devices it is true that attempting to exceed their maximum frequency rating is likely to result in damage. This applies particularly to devices working at high power levels, or things like some highly stressed computer ICs, where raising the clock rate too much can lead to excessive current consumption and overheating.

Many other devices simply do not respond adequately if they are fed with excessively high frequencies. In the case of analogue circuits like amplifiers this may mean that they produce distorted output, or output which has insufficient content at the higher frequencies. Digital circuits may make logical errors, or provide poor quality output (think "eye closure").

This might merit a bit more explanation, but your comment about never having seen a square wave in your practical life puzzles me.
Have you never seen one at all, or are you referring to the obvious truism that nobody has seen one, because a truly square wave is impossible to realise?

 

but your comment about never having seen a square wave in your practical life puzzles me. Have you never seen one at all, or are you referring to the obvious truism that nobody has seen one, because a truly square wave is impossible to realise?

Thank you, MrChips, Adjuster.

@Adjuster: What I wanted to say was that in nature I've never seen square waves, saw tooth waves, etc. Water ripples are close to sinusoidal waves which means sine waves do exist in nature. It seems squre waves etc. have been simply invented by human to make use of their special characteristics.

Best regards
PG

 

It may surprise you to discover that an ideal square wave is composed of a sine wave of the fundamental frequency, plus all of the odd harmonics of the fundamental frequency.
http://en.wikipedia.org/wiki/Square_wave
This is a direct link to the 2nd image down; it's an animated GIF that demonstrates what happens as more harmonics are added to the fundamental frequency. The more harmonics, the closer the wave approaches an ideal square wave:
http://upload.wikimedia.org/wikipedia/commons/f/f8/SquareWave.gif

This implies that an ideal square wave requires unlimited bandwidth, which is of course impossible.