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Conclusion

This free course provided an introduction to studying Health and Social Care. It took you through a series of exercises designed to develop your approach to study and learning at a distance and helped to improve your confidence as an independent learner.


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4 Audio clip 3: Enid Francis

Enid Francis lived in a modern residential area on the outskirts of Derby. She shared a house with her husband, Wally, and two grown-up sons, Mark and John. Her husband had had to give up work eighteen months before his retirement, because of a heart complaint. Their two sons, aged 35 and 32, were both autistic. Enid's day was organised around meeting their needs for care and support. On weekdays, they attended a day centre, which she would have to get them ready for. When they came home in t
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3.2 Health and the middle class

In contrast, a study which focused on white, middle-class men and women between the ages of 35 and 55 (Saltonstall, 1993) found that respondents' views of health were closely connected to wellbeing, and this condition of being was related to ‘capacity, performance and function’ (p. 8). Saltonstall reports that the respondents, both male and female, catalogued what he called a ‘health inventory’ which included things they felt they had and things they thought they were expected to do t
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Acknowledgements

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence.

The material acknowledged below is Proprietary and used under licence (not subject
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5.4 Discussion

We seem to have travelled a long way from the Industrial Revolution in Europe, but many of the impacts on New Zealand's ecosystems described here can be traced, in part at least, to reverberations from these developments.

What lessons can be drawn from this example? Perhaps I should start by emphasising this is not meant to be a complete account of the environmental history of New Zealand. For example, I have not discussed any responses from the population once they realised that harm w
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Learning outcomes

After studying this course, you should be able to:

  • use the sign graph diagramming technique to develop and communicate a systemic understanding of complex situations

  • identify feedback relationships as fundamental controllers within systems and as points of intervention to enact change.


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3.3 Types of quantitative systems model

There is a wide range of quantitative models, of varying degrees of sophistication and complication. In this pack, we will only cover those that I think you are likely to encounter in systems studies or could use to good effect. The techniques available subdivide broadly into two major classes, static models and dynamic models. The distinction between these will become clearer as you look at some detailed examples. Essentially, dynamic models are those where the set of calculations comprising
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2.2 Taking responsibility for your own learning

Not much of this unit conforms to the traditional pattern I mentioned earlier – the theory-example-exercise pattern. In particular, you will find you are expected to discover much of it for yourself. Why is this? This is a legitimate question and deserves a full answer. One year, a student at a residential summer school complained I had not taught him properly. I was, he told me, an expert and so why did I not demonstrate how to tackle the problem he was working on and pass my expertise on
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8.3.3 Reactive ion etching: chlorine/argon plasma etching of aluminium

In a reactive ion etch (RIE), a chemical reaction is used to weaken the bonding of the surface of the material and assist the sputtering process. This combines the high rate and selectivity of a gas-phase etch with the directionality of a sputter etch.

For example, consider aluminium etched anisotropically by a Cl2/Ar mixed-gas plasma, which etches at up to 1 μm min−1:

  • Power pumped into the plasma breaks the gases up, rel
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8.2 Wet etches: acids and bases

The simplest etches use a liquid solvent that converts the material into a soluble compound or a gas. Unfortunately, most materials used in micro-devices have few soluble compounds, so some very aggressive chemicals are needed to attack them. Here is a list of some of the most commonly used ones:

  • Hydrofluoric acid (chemical formula HF) is used to convert silicon dioxide into water-soluble H2SiF6 (plus some hydrogen and water). It
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8.1 Introduction

Etching is central to all forms of micro-device production, from microelectronics and memory through to microsystems technology. Although materials, geometries and feature sizes vary widely, etch processes have a few common features and requirements:

  • Etching acts by converting solid material into a gas or a liquid that can be pumped or flushed away.

  • It is usually restricted to the openings in a lithographically defined mask, and since th
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7.4.7 Deposition of patterned films: lift-off and damascene

We have assumed throughout this section that the deposited film will cover the entire wafer surface and that its patterning will be performed by subsequent lithography and etching steps. However, some materials, most notably copper, can be very difficult to remove with micrometre-scale precision or better, making this sequence extremely difficult. Since copper, with its high electrical conductivity and good chemical properties, is increasingly used in microelectronic device fabrication, anoth
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7.4.6 Molecular beam epitaxy (MBE)

Where a suitable ALD chemistry cannot be found, or where cleanliness and high crystallinity are required, molecular beam epitaxy may be necessary. This is more akin to evaporation than to CVD, with multiple molecular beams of the separate chemical constituents each focused onto the hot wafer surface. Deposition is performed under extreme vacuum conditions (10−11 mbar) to prevent any contaminants from being incorporated, and the substrate must present a perfect cleaved crystal fac
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7.4.5 Atomic layer deposition (ALD)

For very thin conformal films, where rate is unimportant but precise thickness control is critical, a form of CVD allows deposition one monolayer at a time. One precursor gas is introduced into the chamber, which is then pumped away leaving only a monolayer adsorbed onto the wafer and chamber walls. The second precursor gas can then be supplied to complete the reaction at the surface, and then this gas is pumped away along with any gaseous reaction products. This cycle is repeated several tim
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7.4.4 Plasma-enhanced CVD (PECVD)

In PECVD a plasma is initiated in the CVD chamber, usually by supplying an RF voltage to the platen on which the wafer sits – the chamber geometry is similar to a reactive ion etch chamber. Ions are accelerated from this plasma onto the wafer surface, so that the CVD reaction is initiated not only by heating the wafer, but also by the energy imparted as the ions land. This allows high-quality film deposition at much lower wafer temperatures and higher deposition rates than unenhanced CVD, w
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7.4 Depositing compounds

As well as conducting metal layers, device fabrication requires dielectric, insulating materials and these are mostly chemical compounds rather than simple elements or alloys. By far the most widely used of these is silicon oxide (either as a glass or as crystalline quartz), but other oxides and nitrides are also common, plus polymers and a selection of more exotic materials.

Such compounds generally have very high melting points, or decompose under heating, so cannot be deposited by ev
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7.3.5 Ion beam deposition

PVD still has some limitations, however. It must operate in a gaseous atmosphere (to provide the plasma) so is not well suited to the long-throw, directional line-of-sight mode accessible to low-pressure evaporation. Also, if magnets behind the target are used to generate a magnetic field for magnetron sputtering the technique cannot be easily used to deposit magnetic metals such as nickel and cobalt, owing to the influence from the magnetic field on the deposition process.

In an altern
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7.3.4 Physical vapour deposition (PVD), sputtering

An ion hitting a metal surface after acceleration through more than 100 V will not stick or bounce off but will burrow into the surface, splashing atoms outwards. This is known as sputtering and provides a versatile alternative to thermal evaporation for metal-vapour deposition: more controllable, with adjustable uniformity, able to cope with alloys and high-melting-point metals and suitable for production-line automation. Given these advantages, it is also worth the effort to heat the
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7.3.2 Evaporation

The simplest vacuum deposition technique is to heat an ingot of metal in a crucible under vacuum, releasing metal vapour that coats everything in its path. This can be done either under high vacuum (< 0.1 mbar), in which case only surfaces in a line of sight from the source will be coated, or in a low-pressure atmosphere, when the vapour is scattered by gas atoms and can go around corners, making batch processing of multiple wafers possible.

This rather simple technique is fast and chea
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7.3.1 Electroplating

Electroplating is a relatively fast process, inexpensive and simple, although fairly messy and limited in applicability. The wafer is dipped into a solution with dissolved salts of the metal (e.g. CuSO4 + H2SO4) and is connected to a negative voltage. A positive metal electrode (anode), also in the solution, completes the circuit. Anywhere that current can flow into the wafer surface, metal will be deposited. Plating has several advantages: it will deposit met
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