Reviewed By. Neil Levy - - Philosophy in Review 34 6 Aaron Landry - - Philosophy in Review 35 2 Aaron Landry - - Philosophy in Review 34 5 Aaron James Landry - - Philosophy in Review 30 1 Analyzing the Complexity of Nanotechnology. Patricia Fagan and John Russon, Eds. Aaron James Landry - - Philosophy in Review 31 1 Aaron James Landry - - Philosophy in Review 30 2 Added to PP index Total views 6 , of 2,, Recent downloads 6 months 1 , of 2,, How can I increase my downloads? Sign in to use this feature. This article has no associated abstract.
No categories specified categorize this paper. This difference, however, gave rise to the impassioned analog-propositional debate, whose sound and fury only served to further distract attention from theoretical alternatives that did not fit the information processing paradigm.
Since the mid s its hegemony has been repeatedly challenged, first by connectionism e. The robotic system Murphy , designed by Mel , has some interesting features in that it combines such a connectionist model of visual imagery with a model of trial-and-error learning of motor control, wherein information in the putative image is used to control the reaching behavior of a robotic arm although it is not obvious that imagery, as distinct from visual perception, plays any such role in human reaching.
Nevertheless, Mel and Grush continue to conceive of the image itself as being a two dimensional array of elements, just as the quasi-pictorial theory of Kosslyn does, and, indeed, in support of their models both Mel and Grush follow Kosslyn in appealing to evidence about the spatial properties of imagery and about the involvement of visual areas of the brain in imagery.
Thus, despite the fact that Mel and Grush situate their accounts of imagery in the context of motor control rather than of visual cognition, they remain quasi-pictorial accounts, and are, in most respects, considerably less developed than though perhaps consistent with the version of quasi-pictorial theory developed by Kosslyn.
As such, they share most of the virtues of Kosslyn's version, and are subject to the same objections see supplement: The Quasi-Pictorial Theory of Imagery, and its Problems. Dynamical systems theory has also had relatively little to say about imagery, although Freeman has sketched an account of olfactory imagery in terms of neural dynamics. He explicitly distances himself from both sides of the analog-propositional debate, and makes appeal instead to the concept of search image as used in the science of Behavioral Ecology.
A search image is to a first approximation a specific, learned recognitional capacity, or a form of selective attention, that leads a predator species to recognize and preferentially prey upon members of the more abundant prey species in its environment, whilst largely failing to notice less abundant types of potential prey Tinbergen, ; Atema et al. However, it is less than clear that Freeman is justified in conflating this concept of search image with that of mental image, as used in folk psychology and cognitive science. It is mainly the rise of situated and embodied approaches to cognition that has challenged the information processing approach to perception, and enabled the re-emergence and further development of enactive imagery theory.
During the s, robotics researchers interested in creating robots to operate in real wold environments were finding that getting a machine to process information from sensory transducers into an internal representation of its surroundings that would provide a suitable basis for action planning was a very difficult computational problem. Indeed, some became convinced that, even if it could be done in principle, in practice the process would be unacceptably slow, unreliable, and computationally expensive by the time the robot knew what was going on, things would have changed.
Instead of attempting to build up detailed internal representations of their environment, robots began to be designed to deploy their sensors purposively, to actively seek out just the specific information needed at that particular moment for making an impending behavioral decision e. At around the same time, a number of neuroscientists, perceptual psychologists, and philosophers began, for diverse reasons, to converge on a similar view of human vision Ramachandran, ; O'Regan, ; Churchland et al.
We do not have our sense of the immediate perceptual presence of the world because we have a representation of it in our heads, but rather because these routines operate for the most part so quickly and effortlessly that virtually as soon as we want to know some perceptually available fact, we are able to discover it. Thomas b argues that enactive theory can explain experimental cognitive psychology's findings about imagery see sections 4. It has also been argued that enactive theory can provide a more satisfactory explanation of the neurological evidence about imagery i.
Other relevant evidence comes from studies of eye movements during imagery. Saccades are quick, mostly unconscious, flicks of the eyes, which are now known to play an important role not only in vision, but in visual imagery as well. It has also become apparent that saccades and perhaps other types of eye movement too play a significant role in visual mental imagery. Furthermore, imagery is disrupted to a greater or lesser degree if someone who is holding an image in their mind either restrains themselves to the limited degree that this is possible from making eye movements, or else deliberately moves their eyes in an image-irrelevant way, thus disrupting the spontaneous saccadic pattern Antrobus et al.
This issue has been much researched lately, not so much because of its significance for our understanding of imagery, but because of its possible relevance to the understanding of the psychotherapeutic technique known as EMDR Eye Movement Desensitization and Reprocessing , which is widely used in the treatment of Post-Traumatic Stress Disorder PTSD , and which may perhaps owe its effectiveness largely to the fact that deliberate eye movements tend to disrupt any concurrent imagery.
Although the mechanisms and real therapeutic effectiveness of EMDR remain controversial for negative opinions, see: Lohr et al. Although all subjects formed images of the same figures, some originally formed them on the basis of verbal descriptions, whereas others were shown separate segments of the entire structure to be visualized, and asked to assemble them mentally into the complete figure.
The PET scan was not taken at the time the images were originally formed in one or other of these ways, but when they were later recalled. According to the experimenters, enactive theory holds that when someone recalls a mental image they re-enact what they did at the time of its original formation, and since the two subject groups originally formed their images in very different ways, the theory predicts that the two groups should display radically different patterns of brain activation at the time of recall.
In fact, however, no marked differences were seen. This is claimed to constitute a refutation of the enactive theory. It rests, however, on a demonstrable misunderstanding of the theory. No version of enactive imagery theory holds either explicitly or implicitly what these experimenters claim it holds: that recall of mental imagery is constituted by re-enactment of whatever was the original act of image formation. What enactive theory in fact holds is that imagery recalled or otherwise is constituted by partial enactment of the perceptual acts that would be carried out if one were actually perceiving whatever is being imagined Johansson et al.
It is true that in the most straightforward and paradigmatic case of mental image formation — the direct recall of an earlier perceptual experience of something — enactment of what one would be doing if actually perceiving that thing is equivalent to re -enactment of what one did during the original perceptual episode. However, this equivalence clearly breaks down in most other circumstances, including those of the experiment in question.
Since both groups of subjects in the experiment under discussion were supposed to be recalling an image of the same geometrical pattern when their brains were scanned, enactive theory actually predicts that the neural activity due to the recalled image should be much the same in each group, just as was found. Quite apart from empirical evidence, certain distinctively philosophical advantages have been claimed for enactive theory. It has been suggested that it is better able than its rivals to explain imaginal consciousness Ellis, ; Thomas, b, , ; Bartolomeo, , and Thomas , a, b, argues that enactive theory can provide the basis for an understanding of the concept of imagination , whereas quasi-pictorial theory and description theory cannot see also: Blain, ; Agnati et al.
Traditionally, both philosophers and the folk have thought of the imagination as a mental faculty responsible both for mental imagery, and for the most admired forms of artistic and other creativity.
It has also been suggested Newton, , ; Thomas, b, , ; see also Heil, ch. However, if mental images are as just about everybody believes a species of mental representation, these latter claims are at odds with the idea that mental representations are token identical to brain states. The majority of cognitive scientists and sympathetic philosophers remain firmly committed to that idea, and perhaps it is largely for that reason that enactive theory remains a minority viewpoint.
Certainly it has yet to receive anything like the amount of attention either supportive or critical that experimenters and theorists have devoted to quasi-pictorial and description theories. The analog-propositional debate and the enactive theory of imagery concern themselves primarily with the nature and underlying mechanisms of the phenomenon, and have thus had relatively little direct impact on views about the function of imagery in cognition.
Thus neither of these theories did much to challenge the post-Wittgensteinian consensus see section 3. Some neuroscientists and psychologists have been little moved by this consensus. However, as these authors did rather little to address the arguments that have led most contemporary philosophers to think that imagery cannot be representationally basic, their views in this regard have had relatively little impact on philosophy.
Ellis outlines a theory of how the meaningfulness of language may be grounded in imagery that appears to meet at least some of the stock objections see section 3. Although Barsalou denies that the perceptual symbols of his theory can be straightforwardly equated with mental images mainly because he holds that they may sometimes be active in cognitive processes without our being conscious of them [ 52 ] he clearly conceives of them in a way very close to traditional conceptions of imagery, and certainly as being the immediate causes of our imagery experience when we actually do have it.
His detailed suggestions about these questions have aroused much interest. Like Barsalou and, indeed, Locke , he does not take any strong position as to the inherent nature of images or perceptual symbols and thus avoids embroiling himself in the analog-propositional debate and its aftermath. Instead, he confines himself to trying to show that it is plausible that our fundamental concepts are perceptual in their genesis and character, a view that he is quite happy to acknowledge is very close to the traditional imagery theory of cognition.
Prinz deals ingeniously with many of the standard philosophical objections to theories of this sort, and he sidesteps what has been the main philosophical objection to image theories of concepts by avoiding committing himself to the resemblance theory of representation see section 3. Instead, he suggests that his account of perceptual representations can be combined with a version of the causal or covariation theory of intentional content developed by Fodor , , Dretske , , and others.
Gauker , by contrast, aligns himself more closely with the mainstream of twentieth century philosophy see section 3. Nevertheless, he holds that mental imagery plays a crucial role in human cognition and its development, because it forms the basis of a non-conceptual type of thought unfortunately, as he admits Gauker, p. Other recent work has sought to explore the relationship, or lack thereof, between current conceptions of mental imagery and the more resonant, but more nebulous, notion of imagination and related, or putatively related phenomena or concepts such as dreams, hallucinations, insight, and creativity White, ; Brann, ; Finke et al.
Perhaps the most ambitious claims in this regard are those of Arp , , who comes at the matter from the controversial perspective of evolutionary psychology. From this perspective, it is in large part thanks to our capacity to form and manipulate mental imagery that humankind has been able to out-compete rival species, and develop our complex cultures and technologies. Aristotle, General Topics: psychology behaviorism cognitive science consciousness consciousness: and intentionality intentionality introspection language of thought hypothesis memory mental content mental representation perception: the contents of perception: the problem of.
Pre-Scientific Views of Imagery 2. Imagery in the Age of Scientific Psychology 3. Imagery in Cognitive Science 4. Further discussion of phenomena akin to, or sometimes confused with, mental imagery: Supplement: Other Quasi-Perceptual Phenomena 2. Pre-Scientific Views of Imagery It seems likely that mental imagery has been discussed for as long as humans have been trying to understand their own cognitive processes. Indeed, his famous and influential attack in The Principles of Human Knowledge on the possibility of abstract or general ideas clearly derives most of its persuasiveness from the assumption that ideas are like pictures: For my self I find indeed I have a Faculty of imagining, or representing to myself the Ideas of those particular things I have perceived and of variously compounding and dividing them.
I can consider the Hand, the Eye, the Nose, each by itself abstracted or separated from the rest of the Body. I cannot by any effort of Thought conceive the abstract Idea above described. And it is equally impossible for me to form the abstract Idea of Motion distinct from the Body moving, and which is neither Swift nor Slow, Curvilinear nor Rectilinear; and the like may be said of all other abstract general Ideas whatsoever. Principles , Introduction X. Or again, a general idea of a triangle must be neither Oblique nor Rectangle, neither Equilateral, Equicrural, nor Scalenon, but all and none of these at once?
Unfortunately, however, This schematism of our understanding, in its application to appearances and their mere form, is an art concealed in the depths of the human soul, whose real modes of activity nature is hardly likely ever to allow us to discover, and to have open to our gaze. Imagery in the Age of Scientific Psychology When psychology first began to emerge as an experimental science, in the philosophy departments of the German universities in the late 19th century, and soon after in the United States, the central role of imagery in mental life was not in question.
In particular: The subjects frequently reported that they experienced certain events of consciousness which they could quite clearly designate neither as definite images nor yet as volitions. In reality, they are as unmethodical as possible; they possess none of the special features by which we distinguish the introspections of experimental psychology from the casual introspections of everyday life.
Wundt, quoted and translated by Titchener, Original German, Today, it is largely thanks to Wittgenstein's efforts that, an imagistic account of thinking such as is outlined in Russell's Analysis of Mind Lecture X [Russell, ] or elaborated in H. Price's Thinking and Experience [Price, ] is usually no more felt to deserve critical attention than is, say, a geocentric account of the universe.
However, in order to avoid all ambiguity, we must repeat at this point that an image is nothing else than a relationship. The imaginative consciousness I have of Peter is not a consciousness of an image of Peter: Peter is directly reached, my attention is not directed on an image but on an object Sartre, p. Imagery in Cognitive Science A revival of interest in imagery was an important component of the so called cognitive revolution in psychology during the s and early s, a period when the Behaviorist intellectual hegemony over the field was broken and the concept of mental representation was established as central and vital to psychological theorizing Baars, ; Gardner, ; but see also Leahey, Further discussion: Supplement: Representational Neglect 4.
Bibliography For reasons of space and convenience, the bibliography has been divided into three parts: The supplement Mental Imagery Bibliography is an extensive, but inevitably incomplete, bibliography of the science and philosophy of mental imagery. Many, but not all, of the works listed in it are discussed, or at least cited, in the main text of the entry, or in its supplements.
Many of the items are annotated. The supplement Bibliography of cited works not about mental imagery lists works cited in the text of the entry, or in its supplements, but that themselves have little or nothing directly to say about mental imagery. The Select Bibliography below consists only of particularly seminal or influential contributions to the imagery literature, or works that provide particularly useful reviews or collections of aspects of this literature.
It does not include all the works cited in the text of the enty and supplements for which, see the two supplementary bibliographies. Also, many well known classics of philosophy have not been included here, even though they may have a good deal to say about imagery, and may have had a significant influence on how the phenomenon is understood. Such works, together with many other relevant ones, are listed in the supplement Mental Imagery Bibliography. Perceptual Symbol Systems with commentaries and author's reply. Behavioral and Brain Sciences 22 — Cortex 38 — Reprint available online Reviews the clinical evidence on deficits in visual mental imagery and related deficits in visual perception resulting from brain injury.
He concludes that the evidence is not consistent with the quasi-pictorial theory of Kosslyn , , but favors an enactive theory. Unilateral Neglect of Representational Space. Cortex 14 — The first scientific description of the phenomenon of representational neglect: brain damaged patients who ignore things to their left also ignore the left side in their imagery.
Can Mental Images be Ambiguous? A striking experiment revealing an important disanalogy between mental images and pictures; but see Peterson et al. L'Homme Treatise of Man. Facsimile of the original French, together with an English translation by T. An abridged translation, by R.
Stoothoff, is also available in J. Cottingham, R. Murdoch Trans. Cambridge: Cambridge University Press, Descartes' mechanical theory of human physiology, including a mechanistic account of imagery closely akin to the modern quasi-pictorial theory.
Mental Imagery (Stanford Encyclopedia of Philosophy)
The work is thought to have been written in or before , but was not published until Principles of Mental Imagery. Useful textbook of the experimental cognitive psychology of imagery. The Language of Thought. New York: Thomas Crowell. Paperback edition: Harvard University Press, The main thesis of this very influential book is that cognition depends upon an unconscious, language-like representational system innately built into the brain, and which Fodor calls mentalese.
However, it also includes a substantial and also very influential section on imagery arguing that imagery representations probably have a real role in cognition, but that images which he takes to be picture-like cannot be unambiguously meaningful in their own right, and therefore must derive their semantics from mentalese: they function in cognition as "images under descriptions. Statistics of Mental Imagery. Mind 5 — Reprint available online Pioneering individual differences survey of imagery vividness. Galton claims to have found that many intellectuals, and scientists in particular, have very weak visual imagery, or even lack it altogether.
Imagery: The Return of the Ostracised. American Psychologist 19 — Influential account of the historical vicissitudes of the concept of imagery in scientific psychology. A salutary demonstration of the effects of demand characteristics on imagery experiments. Experimental results can be significantly distorted by even very subtle cues as to the experimenters' expectations. Image and Mind. Detailed statement and defence of the computational version of quasi-pictorial theory of imagery, which has been extremely influential.
Updates the quasi-pictorial theory with an account of how imagery may be neurologically embodied. The Case for Mental Imagery. Oxford: Oxford University Press. A relatively succinct and accessible defense of the quasi-pictorial theory of imagery. The Mind of a Mnemonist. Translated from the Russian by L. New York: Basic Books. Imagery and Consciousness. Academic Press. A textbook that usefully summarizes much experimental evidence.
Covers quasi-pictorial , description , and enactive theories, and attempts a theoretical synthesis. Cognition and Reality. San Francisco, CA: W. Imagery and Verbal Processes. New York: Holt, Rinehart and Winston. Republished in — Hillsdale, NJ: Erlbaum. Classic statement of the Dual Coding imaginal and linguistic theory of memory and mental representation, with much empirical evidence on the mnemonic effects of imagery.
Paivio's work together with Shepard's mental rotation experiments probably played the key role in re-establishing imagery as a scientifically wothwhile topic of investigation in cognitive science, aftre the era of Behaviorist neglect of the phenomenon. New York: Oxford University Press.
A major restatement and defense of Dual Coding Theory. American Journal of Psychology 21 — A famous study showing that mental images can be confused with faint percepts under certain, special conditions. See Segal , for a modern partial replication. Furnishing the Mind: Concepts and their Perceptual Basis. Defends an empricist theory of concepts, closely akin to the traditional image theory of ideas , but updated in the light of cognitive science.
Strongly influenced by the work of Barsalou Psychological Bulletin 80 1— A seminal attack on pictorial accounts of imagery. Psychological Review 88 16— Mental Imagery: In search of a theory. Behavioral and Brain Sciences 25 — — including commentaries and reply. Reprint available online A major restatement and updating of Pylyshyn's conceptual and empirical objections to pictorial theories of imagery, including a critique of recent claims e.
Kosslyn, ; Kosslyn, Pascual-Leone et al. Mental Imagery. Psychology Press: Hove, U. Useful textbook concisely surveying the cognitive psychology of imagery, including individual differences research. The Concept of Mind. London: Hutchinson. Chapter 8 contains a seminal critique of pictorial accounts of imagery and questions the traditional concept of imagination as the image producing faculty. It is suggested that both imagination and imagery are conceptually related to pretending. The Psychology of Imagination. Translated from the French by B.
Frechtman, New York: Philosophical Library, Presents Sartre's own positive theory of imagery and imagination. Argues for the intentionality of imagery, and holds that mental images are not inner objects. Amityville, NY: Baywood. A collection of essays on therapeutic techniques that make use of imagery.
The Mental Image. American Psychologist 33 — Mental Images and Their Transformations. A useful compendium of the seminal work by Shepard and his students on the mental rotation of images and related phenomena. Mental Rotation of Three-Dimensional Objects. Science — A classic psychological experiment.
The first, most striking, and best known of the mental rotation studies. Together with the work on the mnemonic effects of imagery see Paivio, this played a major role in re-inspiring scientific interest in imagery research. Slezak, T. Clark Eds. Norwood, NJ: Ablex. An empirically well informed philosopher makes the cognitivist case against pictorialism.
A valuable supplement to Pylyshyn's arguments. Are Theories of Imagery Theories of Imagination? Cognitive Science 23 — Preprint available online Discusses cognitive theories of imagery in the light of their relevance to theories of imagination and its role in creative thought. Proposes and defends a "perceptual activity" enactive theory of imagery, arguing that is both empirically and conceptually superior to both quasi-pictorial and propositional theories.
The Imagery Debate. However, it fails to look seriously beyond this context, and is occasionally unreliable on historical and empirical issues. Psychology as the Behaviorist Views It. Psychological Review 20 — Questions the very existence of imagery. See Watson b for more detail. The Language of Imagination. Oxford: Blackwell. Part 1 is an excellent, if selective, concise history of the concept of imagination in philosophy. Part 2 argues in the teeth of the strong historical consensus detailed in part 1 that there is no conceptual connection whatsoever between imagination and imagery.
See Thomas a for a critique of this view. Philosophical Investigations. Rhees, trans. Contains a powerful and very influential critique of the imagery theory of linguistic meaning. The Art of Memory. London: Routledge and Kegan Paul. A silicon substrate is oxidized so that a layer of silicon oxide is created, with part of this layer is etched away the parts that are not supposed to be etched away, are masked off; for that some technologies are available, of which the lithographic process is a well-known.
Through these 'windows' dopant impurities are introduced into the silicon. Then another oxide layer is grown and new windows are created, through which again at certain places dopant impurities can be introduced.
Join Kobo & start eReading today
Thus several layers of p- and n-type silicon can be made. In this section, firstly, a historical description of the invention and development of LOCOS in a number of steps will be presented 5. In section 4. The invention of LOCOS can be mentioned as a good example of the role of serendipity in technological developments. In , Dr. Else Kooi, a chemist who had joined the Nat. To the contrary, he had hoped that the underlying layer had oxidized because he had heated a silicon substrate covered by a silicon nitride layer to see if a silicon oxide SiO 2 layer would grow.
This thermally grown silicon oxide layer would make a better interface with the silicon nitride layer than a vapor deposited layer. The nitride layer was important for masking against impurities and as a protection against corrosion the passivation layer. To his surprise, though, Kooi found that only the backside of the silicon substrate, where there was no silicon nitride, had oxidized. Immediately, Kooi realized the possible impacts of what he had found by accident. By heating silicon that was only partially covered by silicon nitride, he could grow silicon oxide precisely at places where there was no silicon nitride.
Removing the silicon nitride would then leave a semi-conducting structure that was very flat because the silicon oxide had sunk halfway into the silicon substrate silicon nitride has 2. That was useful because in the production of semi-conducting devices the main rule was: the flatter, the better this results in more reliable interconnect patterns. Besides that, the sunken silicon oxide would also serve as a good separator insulator between the areas left and right from the silicon oxide layer.
That too was useful, as good insulation is another important requirement for reliable semi-conducting structures. The combination of these two properties made Kooi recognize the potential of his finding. In figure 2, the principle of the LOCOS technology, as it was ultimately published after the series of problems had been solved, is shown. The first problem was etching away the silicon nitride after the oxidation process.
Apart from hydrofluoric acid nothing seemed to remove the silicon nitride, but that also removed the silicon oxide. Then Kooi remembered that in a previous experiment he had used lead oxide PbO as a catalyst to make oxidation occur at low temperatures. When he did the same in the LOCOS process he found that the resulting lead glass could easily be dissolved in diluted hydrofluoric acid, which did not hurt the silicon oxide. This problem emerged when LOCOS was used to produce an array of diodes for a vidicon television pickup tube.
Several of the diodes appeared to leak, which was the cause of white spots in the video pictures. By oxidizing more severly than necessary Kooi found out that silicon oxide spots would grow in defects in the silicon nitride film and lift up the edge of the silicon nitride as a chisel would do thus causing mechanical stress that resulted in cracks in the concave corners. A solution was found in creating a thin silicon oxide layer between the silicon and the silicon nitride by thermal oxidation.
This extra layer reduced the effects of silicon oxide spots in silicon nitride defects. The third problem was known as the 'bird beak' and 'bird head' problem. These names were given by Jo Appels, one of Kooi's assistants, who had come up with a method to produce slices of LOCOS structures that could be inspected through a microscope. Beaks and heads are structures that emerge when growing SiO 2 surrounded by other structures seeks a way out.
These beaks and heads, of course, disturb the flatness of the overall structure. Kooi's intuitive response was the desire to 'shave off' such beaks and heads. It would take several years until a way was found to fulfill that desire and etch them off namely by first depositing a borate-phosphate-silicate glass layer over the beak or head and then etching away both this layer and the underlying beak or head.
From scanning electron microscope images of these ribbons, Kooi could derive that they had to be narrow regions of non-oxidized silicon. This puzzled Kooi, because there was no obvious reason why the silicon did not want to oxidize at those places. Kooi's assumption was that somehow masking material at those spots had covered the silicon. Silicon nitride was, of course, the first option for that material. But how could it get there? To explain that Kooi came up with a model in which nitrogen transfers from the nitride oxidation mask to the interface between the silicon and the silicon oxide.
Near the LOCOS edge not much nitrogen would react with silicon because of the competition of the oxidation reaction, but at some distance from the LOCOS edge, the nitrogen could well form new nitride and serve as a mask, thus causing the formation of the 'white ribbons'. If the nitride ribbon was not removed, oxidation in that area would not be effective. Experiments were done to confirm this.
Kooi's solution to the ribbon problem was to over-etch so that not only the nitride oxidation mask would be removed but also the nitride at the ribbon site. This solution was inspired by the previous experience that the ribbon effect had not happened when some over-etching had occasionally been applied. The story of the development of LOCOS in Philips does not quite end here, but we already have sufficient material for reflection on the nature of the technological knowledge in this case study.
Now we will try to identify what types of knowledge can be distinguished in the steps that have been described above. Let us now consider what knowledge was used by Kooi to take each of the hurdles that we have seen in the LOCOS story as described in section 4. The first step in the process was the recognition of the potential of silicon nitride to serve as an oxidation mask for silicon substrates.
In , Kooi was able to make a connection between several things he knew. By inspecting the heated substrate, Kooi had observed that the silicon under the silicon nitride had not oxidized. From this he derived that the nitride had protected the underlying silicon against oxidation.
This he related with the function of a mask. He knew that masks were used to make oxidation patterns on silicon substrates this was the basic principle of planar technology. He knew that silicon oxide has stabilizing properties that make it suitable to function as a protecting coating, as had been found by Atalla, Tannenbaum and Scheibner in a paper that Kooi knew and had inspired him to do his own Ph. He also knew a material property of silicon nitride, namely that it was a better protector against invading impurities during oxidation than silicon oxide was.
Finally, he knew that silicon oxide had twice the volume of the original silicon and therefore would sink halfway into the silicon substrate. This would make a rather flat surface, which was good for planar structures it allowed for better contacts with the metal strips that were to be put onto it. All this knowledge together made Kooi realize that using silicon nitride as a mask for making oxidation patterns in silicon oxide would yield rather flat and stable surfaces with few impurities. Those properties fit well with the generally recognized requirements for a planar transistor. He was now able to imagine a process that would result in such a planar structure.
Evidently, this is quite a rich combination of knowledge and that is what makes the invention so impressive. Part of the knowledge has to do with the intentionality-bearing function that a material can fulfill.
- Passar bra ihop.
- Romanticism in Science: Science in Europe, 1790–1840.
- Recommended for you!
- Developing a strong research-base;
- Mental Imagery.
This knowledge could be 'functional nature knowledge', because it is related to the 'functional nature' properties of the material. In Meijers' terminology, these belong to the relational properties of the artifact or material in this case; see Meijers , p. An example of this type of knowledge is Kooi's insight into the functioning of a mask in planar technology.
Part of the knowledge has to do with material properties.
Technological Knowledge and Artifacts: An Analytical View
This knowledge refers to the physical nature of the material and can be expressed in propositions such as 'impurities do not easily invade into silicon nitride at high temperatures'. This can be called 'physical nature knowledge'. Then there is knowledge to judge whether a material property is suitable for a planar structure. For instance, the fact that silicon oxide sinks halfway into the silicon is good from a flatness requirement point of view, or the fact that silicon nitride shields off underlying silicon from oxidation makes it suitable for serving as a mask in planar technology.
This can be called 'means-ends knowledge'. The knowledge about how to set up a process to produce a planar transistor using the newly found combination of properties first deposit silicon nitride, then oxidize, then remove the nitride , in other words, the knowledge about what actions will lead to the desired result, can be called 'action knowledge'. This first step of the LOCOS process was probably the most crucial and we have seen that it involved quite a rich combination of knowledge. The next steps required combinations of knowledge also, but were less rich.
As we saw the first problem that Kooi met when he tried to control the process of LOCOS, was his unability to etch away the silicon nitride without hurting the silicon oxide. To solve this problem, Kooi made use of previously gained knowledge.
- Dragonfly Falling (Shadows of the Apt, Book 2).
- Shaping concepts of technology : from philosophical perspective to mental images.
From previous experiments in his Ph. He had picked up that idea from a article by Kallander, Flaschen, Gnaedinger and Lutfy. Oxidation under low temperatures was attractive because it prevented already formed junctions between p- and n-regions to be disturbed because of the increasing mobility of the donors and acceptors at higher temperatures.
The lead oxide causes lead glass to be formed and this glass can easily be etched away with the nitride without hurting the silicon oxide. Again we see a combination of knowledge. Kooi knew that the presence of lead oxide made oxidation of silicon happen at lower temperatures 'physical nature knowledge'. He recognized that therefore the lead oxide could serve the function of a catalyst in his LOCOS process 'means-ends knowledge'. He then also knew that the action of adding lead oxide would enable him to complete the LOCOS process 'action knowledge'.
In solving the second problem, the occurrence of cracks in concave corners of LOCOS structures, no knowledge of material properties or of functionalities was involved. Kooi just guessed that creating an extra thin oxide layer would make a better geometry of the structure in which less tensions could emerge in the silicon nitride edge. Here the emphasis seems to be on knowing that the action of creating the extra layer would have a positive effect 'action knowledge'.
The third problem, 'bird beaks' and 'bird heads' was again solved just by imagining a simple action, namely by just 'shaving off' the undesired structures. Here too 'action knowledge' seems to be an appropriate characterization. For solving the fourth problem, the 'white ribbons' that appeared along the LOCOS structure edge, Kooi developed a model that involved knowledge of the behavior of silicon, namely that it rather oxidizes than reacts with nitride when both oxygen and nitride are present. This is what we previously called 'physical nature knowledge'.
His solution was inspired by a previous experience that at that time was not yet related to the 'ribbon' problem, namely, that over-etching would not only remove the nitride oxidation mask but also the nitride. Applying this previous experience to the new problem required recognition of the function of over-etching in such a case 'functional nature knowledge'. One could say that 'means-ends knowledge' played a role in the recognition of the problems. Because Kooi knew what the properties of a planar structure should be, he was able to judge if his LOCOS-made structures were 'good' or 'bad'.
As the purpose of the LOCOS case study was to extend Vincenti's empirical studies into new technological areas, an obvious continuation for reflecting on the empirical data is to see if Vincenti's categories of engineering knowledge apply here too. Vincenti's first category consists of what he called fundamental design concepts.
Although Kooi evidently had this knowledge, it only plays a role in the background. It only seems to become relevant when criteria and specifications are derived from this. But this is a different category in Vincenti's view. This category in the LOCOS case comprises the knowledge that planar structures need to be flat, that the threshold voltage of the transistor structure needs to be sufficiently high, that dimensions should be small because the main aim is to make small structures , and that the structure should be stable.
Vincenti's category of theoretical tools is present in Kooi's knowledge of the material properties of silicon, silicon oxide, silicon nitride and lead oxide, but also in his ability to reason from the properties towards using those for a certain purpose.