Jack Kilby's Chip - the Monolithic Idea
Jack S Kilby
Kilbys first chip
In the summer of 1958 Jack Kilby at Texas Instruments found a solution to this problem. He was newly employed and had been set to work on a project to build smaller electrical circuits. However, the path that Texas Instruments had chosen for its miniaturization project didn't seem to be the right one to Kilby.
Because he was newly employed, Kilby had no vacation like the rest of the staff. Working alone in the lab, he saw an opportunity to find a solution of his own to the miniaturization problem. Kilby's idea was to make all the components and the chip out of the same block (monolith) of semiconductor material. When the rest of the workers returned from vacation, Kilby presented his new idea to his superiors. He was allowed to build a test version of his circuit. In September 1958, he had his first integrated circuit ready. It was tested and it worked perfectly!
Although the first integrated circuit was pretty crude and had some problems, the idea was groundbreaking. By making all the parts out of the same block of material and adding the metal needed to connect them as a layer on top of it, there was no more need for individual discrete components. No more wires and components had to be assembled manually. The circuits could be made smaller and the manufacturing process could be automated.
Jack Kilby is probably most famous for his invention of the integrated circuit, for which he received the Nobel Prize in Physics in the year 2000. After his success with the integrated circuit Kilby stayed with Texas Instruments and, among other things, he led the team that invented the hand-held calculator.
Robert Noyce
Robert Noyce
Robert Noyce came up with his own idea for the integrated circuit. He did it half a year later than Jack Kilby. Noyce's circuit solved several practical problems that Kilby's circuit had, mainly the problem of interconnecting all the components on the chip. This was done by adding the metal as a final layer and then removing some of it so that the wires needed to connect the components were formed. This made the integrated circuit more suitable for mass production. Besides being one of the early pioneers of the integrated circuit, Robert Noyce also was one of the co-founders of Intel. Intel is one of the largest manufacturers of integrated circuits in the world.
Chip Production Today - in Short
Stepping.
Chip production today is based on photolithography. In photolithography a high energy UV-light is shone through a mask onto a slice of silicon covered with a photosensitive film. The mask describes the parts of the chip and the UV-light will only hit the areas not covered by the mask. When the film is developed, the areas hit by light are removed. Now the chip has unprotected and protected areas forming a pattern that is the first step to the final components of the chip.
Next, the unprotected areas are processed so their electrical properties change. A new layer of material is added, and the entire process is then repeated to build the circuit, layer by layer. When all the components have been made and the circuit is complete a layer of metal is added. Just as before, a layer of photosensitive film is applied and exposed through a mask. However, this time the mask used describes the layout of the wires connecting all the parts of the chip. The film is developed and the unexposed parts are removed. Next, the metal not protected with film is removed to form the wires. Finally, the chip is tested and packaged.
When making chips today, a process called "stepping" is often used. On a big wafer of silicon the chips are made one next to the other. The silicon wafer is moved in steps under the mask and the UV-light to expose the wafer. In this way, chip after chip can be made using the same mask each time.
Below is a more sequential description of the process of making a modern integrated circuit. But let us first take a look at the special place where integrated circuits are produced - the clean room.
The Clean Room
Child facing"bunny suit"
The sizes of the components on chips produced in a modern chip fabrication plant are extremely small. For a better understanding of how small they are, pick a hair from your head and cut it in half. Now look at the cross section. On this tiny area, hard to see with the bare eye, you can fit thousands of modern transistors.
With sizes this small, the production of a chip demands precision at an atomic level. Tiny particles like a hair, a speck of dust, a dead skin cell, bacteria or even the single particles in tobacco smoke become huge objects that are big enough to ruin a chip.
Therefore, chip production takes place in a clean room. This is a specially designed room, where furniture is built from special materials that don't give off particles, and where extremely effective air filters and air circulation systems change the air completely up to ten times a minute.
To further prevent contamination, workers wear special suits called "bunny suits." These protective outfits are made of ultra clean material and sometimes have their own air filtering systems. |
