How is a chip designed? Do you know how the designed chip is produced? After reading this article you will have a general idea. Complex and cumbersome chip design process
The process of chip manufacturing is like building a house with Lego, with wafers as the foundation, and then layers of chip manufacturing processes on top of each other, to produce the necessary IC chips (these will be described later). However, without the design, it is useless to have a strong manufacturing ability, so the role of the architect is quite important. But who are the architects in IC design? The next part of this paper is to introduce the IC design.
In the IC production process, IC is mostly planned and designed by professional IC design companies, such as Mediatek, Qualcomm, Intel and other well-known factories, all design their own IC chips, providing different specifications and performance chips to downstream manufacturers to choose. Because the IC is designed by the factory itself, the IC design is very dependent on the technology of the engineer, the quality of the engineer affects the value of an enterprise. But what exactly are the steps that engineers go through when designing an IC chip? The design process can be simply broken down into the following.
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What is a wafer?
In the semiconductor news, there is always a reference to the size of the fabs, such as 8-inch or 12-inch fabs, but what is the so-called wafer? What part does the 8 inch refer to? How difficult is it to produce large scale wafer fabrication? The following will step by step introduce the most important basis of semiconductors - what is the \"wafer\".
wafer is the basis for making all kinds of computer chips. We can compare chip manufacturing to building a house with Lego bricks, by stacking layer after layer, to achieve the desired shape (i.e., the various chips). However, if there is no good foundation, the house will be crooked, not what you want, in order to make a perfect house, you need a smooth substrate. For chip manufacturing, this substrate is the wafer described next.
First of all, recall that when we were playing with Legos as a child, the surface of the building blocks would have a small round bulge, through this structure, we can firmly stack two blocks together, and do not need to use glue. Chips are made in a similar way by attaching subsequent atoms to the substrate. Therefore, we need to find a substrate with a neat surface to meet the conditions required for subsequent manufacturing.
In solid materials, there is a special crystal structure - a single crystal (Monocrystalline). It has the property of having atoms packed tightly together, one after the other, to form a flat atomic surface. Therefore, the use of single crystals to make wafers can meet the above needs. However, how to produce such a material, there are two main steps, namely purification and crystal pulling, after which such a material can be completed.
How to make a single crystal wafer
Purification is divided into two stages, the first step is metallurgical grade purification, this process is mainly to add carbon, in the way of REDOX, the silicon oxide into more than 98% pure silicon. Most metals, such as iron or copper, are extracted in this way to obtain a sufficiently pure metal. However, 98% is still not enough for chip manufacturing and needs to be further improved. Therefore, the Siemens process will be further used for purification, so that the high-purity polysilicon required for the semiconductor process will be obtained.
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Next, it is the step of pulling the crystal. First, the high-purity polysilicon obtained above is melted to form liquid silicon. After that, the single crystal silicon seed is in contact with the liquid surface and slowly pulls up while rotating. As for why the single crystal silicon seed is needed, it is because the arrangement of silicon atoms is the same as the queue of people, and it will need to line up so that later people can correctly arrange, and silicon seed is an important queue, so that later atoms know how to line up. Finally, after the silicon atoms leave the liquid surface to solidify, the arranged monocrystalline silicon columns are completed.
But what does 8 \"and 12\" mean? He was referring to the diameter of the crystal column we produce, the part that looks like a pencil bar, the surface of which is treated and cut into thin discs. What is the difficulty in making large wafers? As mentioned earlier, the process of making the crystal column is like making marshmallow, rotating as it forms. If you have made marshmallows, you should know that it is very difficult to make large and solid marshmallows, and the process of crystal pulling is the same, the speed of rotation and temperature control will affect the quality of the crystal column. Therefore, the larger the size, the higher the speed and temperature requirements for crystal pulling, so it is more difficult to make high-quality 12-inch wafers than 8-inch wafers.
However, a whole strip of silicon column can not be made into a substrate for chip manufacturing, in order to produce a piece of silicon wafer, then need to use a diamond knife to cut the silicon crystal column into a wafer, and the wafer can be polished to form the silicon wafer required for chip manufacturing. After so many steps, the manufacturing of the chip substrate is complete, and the next step is the step of stacking the house, which is the chip manufacturing. As for how to make chips?
A chip built on top of each other
After introducing what silicon wafers are, at the same time, I also know that manufacturing IC chips is like building a house with Lego bricks, by stacking layer after layer, to create your own desired shape. However, there are quite a few steps in building a house, and the same goes for IC manufacturing. What are the steps in making an IC? This paper will introduce the process of IC chip manufacturing.
Before we begin, we need to understand what an IC chip is. IC, the full name of the Integrated Circuit (Integrated Circuit), by its name we know that it is the design of the circuit, in a stacked way. In this way, we can reduce the area required to connect the circuit. The following is a 3D diagram of the IC circuit, from which it can be seen that its structure is like the beams and columns of a house, stacked layer by layer, which is why IC manufacturing is compared to building a house.
From the 3D profile of the IC chip in the above figure, the dark blue part at the bottom is the wafer introduced in the previous article, from this figure can be more clearly know how important the role of the wafer substrate in the chip is. As for the red and earthy yellow parts, they are where the IC is made to be completed.