From sand to chip: how is a modern semiconductor made?
Reading time: approx. 10min
1) INTRODUCTION
Since 2023 at the latest and the rapid rise of Nvidia $NVDA (+0,66 %) semiconductors and "AI chips" in particular have been the talk of the town. Since then, investors have been chasing after almost every company that has something to do with the manufacture of chips, driving share prices to unimagined heights. However, hardly any investors really know how complex the value chain is within the production of modern chips.
In this article, I will give you an overview of the entire manufacturing process and the companies involved. Even if many of you have a vague idea that the production of modern chips is complex, you will certainly be surprised by how complex it really is in reality.
2) BASIC
The starting point for every chip are so-called wafers [1] - i.e. thin wafers, which usually consist of so-called high-purity monocrystalline silicon. In the field of power semiconductors, which primarily comprises chips for applications with higher currents and voltages, silicon carbide (SiC) or galium nitride (GaN) has recently also been used as the base material for the wafers.
In the so-called front end the actual core components of the chips - the so-called dies - are created and applied to the wafers. The dies are rectangular structures that contain the actual functionality of the later chip. The finished dies are then tested for their functionality and electrical properties. Each die that is found to be good is then integrated into the so-called backend where the individual dies are separated on the wafer. This is followed by the so-called packaging. The individual dies from the front end are then electrically contacted and integrated into a protective housing. In the end, this housing with the contacted die is what is usually called a chip chip.
Now that we have a rough overview of the overall process, let's take a closer look at the individual processes involved in producing the dies on the wafer. This is the area in which most highly complex machines are used and which is usually the most sensitive.
3) FROM SAND TO WAFER
Before wafers made of high-purity silicon can even be produced and the actual process for manufacturing dies can begin, the actual wafer must first be manufactured in almost perfect quality. To do this, quartz sand, which consists largely of silicon dioxide, is reduced with carbon at high temperatures. This produces so-called raw siliconwhich, with a purity of around 96%, is not yet anywhere near the quality required for the production of wafers.
In several chemical processes, which are carried out by Wacker Chemie
$WCH (+0,2 %) or Siltronic
$WAF (-0,31 %) are used to turn the "impure" silicon into so-called polycrystalline silicon with a purity of 99.9999999%. For every billion silicon atoms, there is then only one foreign atom in the silicon. However, this pure polycrystalline silicon is still not suitable for the production of wafers, as the crystal structure in the silicon is not uniform enough. In order to create the right crystal structure, the polycrystalline silicon is then melted again and a so-called ingotwhich is made from monocrystalline silicon is produced. A comparison between raw silicon and the ingot can be found in the following image [3]:
