ABSTRACT
Summary
Technological knowledge can be categorised in various ways. Walther Vincenti uses the following categories: fundamental design concepts, criteria and specifications, quantitative data, theoretical tools, practical considerations and design instrumentalities. Michael Polanyi differentiates between ‘tacit’ and ‘codified’ knowledge. Yet another approach is: knowledge of the physical nature of artefacts, the functional nature of artefacts, the relation between the physical and functional nature of artefacts, and knowledge of processes. Finally one can also relate different aspects of reality to different types of knowledge. An important feature of technological knowledge is its integrated character: a combination of knowledge from different kinds of sciences. One feature that distinguishes technological knowledge from some forms of scientific knowledge is its normative character: the content of the knowledge refers not merely to what is, but also to what should be. However useful technological knowledge has proved to be, it has its limitations. This is partly due to the fact that reality sometimes presents itself in a different way from what it is (think of mirages, for instance), that we sometimes think things are true since we would like them to be true, and that technological knowledge, no matter how broad it is, always contains only a part of reality.
One of the most important inventions in the field of Integrated Circuits (ICs) is the process LOCal Oxidation of Silicon (LOCOS). For many years this process was the industrial standard which more or less compelled every producer of ICs to work with this process. LOCOS is a technology of making ICs from slices of silicon. The essence of this technique is that areas in the silicon are provided with another material that causes an excess or a shortage of electrons in that place. Applying materials of this kind is called ‘doping’. By doping the current can be sent from one place to another. It is important that the materials only enter into the silicon in 116the predetermined places. To achieve this the rest of the silicon surface is screened off. This screening off is effected by letting that surface oxidise. The oxidation therefore has to take place only in parts which later may not contain any doping. In the LOCOS process a thin layer of silicon nitride is first applied locally by means of a lithographic process. This is used as a ‘mask’ during the oxidisation of silicon. In places where silicon nitride is present the underlying silicon is protected against oxidation, and where no silicon nitride is present, oxidation does take place. During the oxidation the oxide layer partly sinks down into the silicon (see Figure 6.1). The LOCOS process https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315696362/968600b2-9ca7-4b48-af5d-54d995719a60/content/fig6_1_B.jpg" xmlns:xlink="https://www.w3.org/1999/xlink"/>
The LOCOS process was developed in Philips’ Physical Laboratory (Nat. Lab.) in Eindhoven (De Vries 2005a). By referring to the documents in the archives one discovers that in the development of this process various types of knowledge were applied. One part of the knowledge was of a very practical nature. The ‘assistants’ (the name for the employees who conducted the experiments) had knowledge of experimenting with silicon. They knew exactly how to set the temperature of an oven to get a good IC. The researchers had knowledge of the mechanisms that take place when silicon oxidises. They knew exactly how they could influence the properties of the oxide layer. Another part of the knowledge was very theoretical. Scientists in another research group did quantum mechanical calculations on this kind of layer. But these scientists had no contact with the group working on LOCOS. In this way it was only later discovered that the work of the quantum theoretical group could have been particularly useful for the LOCOS group which was more experimentally oriented. In short, a chance was lost to bring together different kinds of knowledge.
The example of LOCOS shows that in the development of technology different kinds of knowledge can be distinguished. In this chapter we will be going into the kinds of knowledge and their properties. The important theme of the integration of different kinds of knowledge will also be dealt with.
