Silicon pad design

Abstract

A semiconductor device comprises a pixel area 801 comprising a plurality of active pixels, a gasket seal 804 delimiting the pixel area, and at least one conductive element 814 for electrical connection. The conductive element comprises a plurality of conductive sub‐elements 812A. The sub-elements may have different sizes or shapes to one another. The conductor(s) may comprise an irregular array of sub-elements. The conductor may be within the gasket seal and the conductive material of the conductor may form the seal. The seal may be conductive. There may be a plurality of cells in the device, with one cell group corresponding to the pixels, another cell group corresponding to isolated pixels, and another cell group corresponding to the conductive element(s). the conductive element may be electrically isolated from the pixel area. The seal may be electrically isolated from the pixel area.

Description

FIELD The present disclosure relates to a silicon pad and the design thereof. Broadly, the present disclosure relates to a semiconductor device and a pad therefor. More specifically, the present disclosure relates to a display device and a liquid crystal on silicon spatial light modulator. The present disclosure also relates to a conductive or electrical connection element for a semiconductor device. Yet more specifically, the present disclosure relates to a reference voltage pad for a silicon device. BACKGROUND AND INTRODUCTION Light scattered from an object contains both amplitude and phase information. This amplitude and phase information can be captured on, for example, a photosensitive plate by well-known interference techniques to form a holographic recording, or "hologram", comprising interference fringes. The hologram may be reconstructed by illumination with suitable light to form a two-dimensional or three-dimensional holographic reconstruction, or replay image, representative of the original object. Computer-generated holography may numerically simulate the interference process. A computergenerated hologram may be calculated by a technique based on a mathematical transformation such as a Fresnel or Fourier transform. These types of holograms may be referred to as Fresnel / Fourier transform holograms or simply Fresnel / Fourier holograms. A Fourier hologram may be considered a Fourier domain / plane representation of the object or a frequency domain / plane representation of the object. A computer-generated hologram may also be calculated by coherent ray tracing or a point cloud technique, for example. A computer-generated hologram may be encoded on a spatial light modulator arranged to modulate the amplitude and / or phase of incident light. Light modulation may be achieved using electrically-addressable liquid crystals, optically-addressable liquid crystals or micro-mirrors, for example. A spatial light modulator typically comprises a plurality of individually-addressable pixels which may also be referred to as cells or elements. The light modulation scheme may be binary, multilevel or continuous. Alternatively, the device may be continuous (i.e. is not comprised of pixels) and light modulation may therefore be continuous across the device. The spatial light modulator may be reflective meaning that modulated light is output in reflection. The spatial light modulator may equally be transmissive meaning that modulated light is output in transmission. A holographic projector may be provided using the system described herein. Such projectors have found application in head-up displays, "HUD", and head-mounted displays, "HMD", including neareye devices, for example. The present disclosure relates to silicon pad design particularly for liquid crystal on silicon (LCDS) devices. Pads in LCDS processes are typically subject to design rules, mostly designed to control for die flatness, that limit their materials, structure, stack-up, dimensions and density. They are typically designed with particular uses in mind: wire bonding, anisotropic conductive film (ACF) bonding and use with conductive material for internal reference voltage (VCOM) crossover. Embodiments of the present disclosure relate to the latter use-case. When a non-standard design is required - e.g. to accommodate a new process or to open up the process window - these constraints can be limiting. For example, this can be an issue when developing internal crossover process with silver flakes suspended in epoxy. This has typically put a constraint of needing an unusually large pad - e.g. to accommodate the highly viscous material. A single large expanse of metal falls foul of the design rules of the foundries and usually also of the metal density rules of the design house. SUMMARY Aspects of the present disclosure are defined in the appended independent claims. In general terms, a display device and a method of assembling a display device are provided. The display device comprises a spatial light modulator, such as a liquid crystal on silicon spatial light modulator, and a substrate. The spatial light modulator is mounted on a first major surface of the substrate by an attachment material. The properties of the attachment material are chosen to optimise optical performance of the display device over a large range of environmental conditions, such as temperatures associated with automotive applications. In particular, the attachment material may be chosen to have a selected combination of values of the thermal properties: (i) coefficient of thermal expansion and (ii) thermal conductivity. A display device according to the disclosure may be suitable for use in a picture generating unit or projector, such as a holographic projector. For example, the display device may be used in a system - such as a head-up display (HUD) - which is configured to display a picture to a viewer, without requiring the user to look away from their usual, or required, viewpoint. The display device may be particularly suitable for an HUD system comprised within a vehicle. In the context of a picture generating unit or projector, a spatial light modulator is encoded with an image or hologram of an image and is illuminated with light. Thus, the spatial light modulator modulates the amplitude and / or phase of the incident light according to the image or hologram and outputs spatially modulated light. In embodiments described herein, the spatial light modulator is a phase modulator. In some applications, a spatial light modulator is used in a relatively stable environment, for example in a static arrangement that is maintained at a stable temperature and humidity. However, in some applications, spatial light modulators may be used in less stable environments, for example in a portable arrangement, in which the spatial light modulator may experience substantial variations in temperature, humidity, movement and similar environmental changes. A particular example of such an environment is the inside of a vehicle or automobile, in which there may be extreme temperature variations. In overview, there is disclosed herein multiple small, metallised pads arranged in a larger matrix, each surrounded with non-conducting material. More specifically, a first aspect of the present disclosure is a semiconductor device comprising a pixel area comprising a plurality of active pixel, a gasket seal delimiting the pixel area and at least one conductive element for electrical connection. The conductive element comprises a plurality of conductive sub-elements. The at least one conductive element is also referred to herein as a "pad". The pad may be conductive metallised feature designed for enabling electrical contact to transmit a signal or a potential or current. In some embodiments, it is for controlling the potential of an ITO electrode on glass. There is disclosed herein a solution to the problem of reducing pad size - e.g. when the pad comprises a highly viscous material such as metal flakes in epoxy or resin. The solution disclosed comprises putting together an array of smaller pads that conform to all design rules, but which taken together correspond to a virtual larger pad. Metal density is more easily controlled by adding or removing metal as needed to match the average density. In important embodiments, around the array of pads, an area of non-conducting (floating) material is present to act as a buffer and avoid the risk of shorting to adjacent metal. The solution of the present disclosure offers at least the following advantages: much larger pads are possible; lower metal density in pad area (more easy to balance density across the die); bypasses pad design rules; and allows pads to be used by processes with more viscous metal epoxies. In a first group of embodiments, the pads follow the pixel dimensions rules - for example, as small as 1 micrometre with a gap between of 0.1 micrometres. In a second group of embodiments, the pads need to follow so-called "pad" rules, in which case they have larger dimensions imposed - for example, down to a few 10s of micrometres wide with similar sized gaps. The conductive sub-elements of the plurality of conductive sub-elements may be spatially separated from each other. Each conductive sub-element may be square or rectangular. The conductive sub-elements may be the same size and / or shape as each other. At least two conductive sub-elements of the plurality of conductive sub-elements may have a different size and / or shape to each other. The plurality of conductive sub-elements may form a regular array such as a square or rectangular array. The plurality of conductive sub-elements may form an irregular array. The plurality of conductive sub-elements may each comprise metal. The plurality of conductive sub-elements may be surrounded by a non-conducting material. he plurality of conductive sub-elements may be arranged to have conductive material dispensed thereon to form a connection pad. The conductive material may comprise metal flakes, such as silver or nickel flakes, suspended in epoxy. The conductive element may be disposed outside of the gasket seal - i.e. on the other side of the gasket seal to the pixel array. The conductive element may be disposed within the gasket seal. The conductive material may be disposed within the gasket seal. The conductive material may partially or completely form the gasket seal. The semiconductor device may comprise an array of cells. Cells of a first group of cells may respectively correspond to pixels of the plurality of active pixels. Cells of a second group of cells may correspond to isolated ("dummy") pixels. Cells of a third group of cells may correspond to the conductive element. Cells of the second group may be electrically isolated from all other cells. Cells of the first group of cells (corresponding to the active pixels) may be electrically connected -e.g. on the underside - to a common electrode. The common electrode may be reflective. The gasket seal may be conductive and applied over the third group of cells (corresponding to the conductive element). A subset of isolated ("dummy") pixels may be disposed between the gasket seal and the pixel area. The active pixels of the pixel area are fillable with liquid crystal. The conductive element may be electrically isolated and / or spatially separated from the pixel area. The gasket seal may be electrically isolated from the pixel area. The term "hologram" is used to refer to the recording which contains amplitude information or phase information, or some combination thereof, regarding the object. The term "holographic reconstruction" is used to refer to the optical reconstruction of the object which is formed by illuminating the hologram. The system disclosed herein is described as a "holographic projector" because the holographic reconstruction is a real image and spatially-separated from the hologram. The term "replay field" is used to refer to the 2D area within which the holographic reconstruction is formed and fully focused. If the hologram is displayed on a spatial light modulator comprising pixels, the replay field will be repeated in the form of a plurality diffracted orders wherein each diffracted order is a replica of the zeroth-order replay field. The zeroth-order replay field generally corresponds to the preferred or primary replay field because it is the brightest replay field. Unless explicitly stated otherwise, the term "replay field" should be taken as referring to the zeroth-order replay field. The term "replay plane" is used to refer to the plane in space containing all the replay fields. The terms "image", "replay image" and "image region" refer to areas of the replay field illuminated by light of the holographic reconstruction. In some embodiments, the "image" may comprise discrete spots which may be referred to as "image spots" or, for convenience only, "image pixels". The terms "encoding", "writing" or "addressing" are used to describe the process of providing the plurality of pixels of the SLM with a respective plurality of control values which respectively determine the modulation level of each pixel. It may be said that the pixels of the SLM are configured to "display" a light modulation distribution in response to receiving the plurality of control values. Thus, the SLM may be said to "display" a hologram and the hologram may be considered an array of light modulation values or levels. It has been found that a holographic reconstruction of acceptable quality can be formed from a "hologram" containing only phase information related to the Fourier transform of the original object. Such a holographic recording may be referred to as a phase-only hologram. Embodiments relate to a phase-only hologram but the present disclosure is equally applicable to amplitude-only holography. The present disclosure is also equally applicable to forming a holographic reconstruction using amplitude and phase information related to the Fourier transform of the original object. In some embodiments, this is achieved by complex modulation using a so-called fully complex hologram which contains both amplitude and phase information related to the original object. Such a hologram may be referred to as a fully-complex hologram because the value (grey level) assigned to each pixel of the hologram has an amplitude and phase component. The value (grey level) assigned to each pixel may be represented as a complex number having both amplitude and phase components. In some embodiments, a fully-complex computer-generated hologram is calculated. Reference may be made to the phase value, phase component, phase information or, simply, phase of pixels of the computer-generated hologram or the spatial light modulator as shorthand for "phase-delay". That is, any phase value described is, in fact, a number (e.g. in the range 0 to 2?t) which represents the amount of phase retardation provided by that pixel. For example, a pixel of the spatial light modulator described as having a phase value of ti / 2 will retard the phase of received light by ti / 2 radians. In some embodiments, each pixel of the spatial light modulator is operable in one of a plurality of possible modulation values (e.g. phase delay values). The term "grey level" may be used to refer to the plurality of available modulation levels. For example, the term "grey level" may be used for convenience to refer to the plurality of available phase levels in a phase-only modulator even though different phase levels do not provide different shades of grey. The term "grey level" may also be used for convenience to refer to the plurality of available complex modulation levels in a complex modulator. The hologram therefore comprises an array of grey levels - that is, an array of light modulation values such as an array of phase-delay values or complex modulation values. The hologram is also considered a diffractive pattern because it is a pattern that causes diffraction when displayed on a spatial light modulator and illuminated with light having a wavelength comparable to, generally less than, the pixel pitch of the spatial light modulator. Reference is made herein to combining the hologram with other diffractive patterns such as diffractive patterns functioning as a lens or grating. For example, a diffractive pattern functioning as a grating may be combined with a hologram to translate the replay field on the replay plane or a diffractive pattern functioning as a lens may be combined with a hologram to focus the holographic reconstruction on a replay plane in the near field. Although different embodiments and groups of embodiments may be disclosed separately in the detailed description which follows, any feature of any embodiment or group of embodiments may be combined with any other feature or combination of features of any embodiment or group of embodiments. That is, all possible combinations and permutations of features disclosed in the present disclosure are envisaged. BRIEF DESCRIPTION OF THE DRAWINGS Specific embodiments are described by way of example only with reference to the following figures: Figure 1 is a schematic showing a reflective SLM producing a holographic reconstruction on a screen; Figure 2A illustrates a first iteration of an example Gerchberg-Saxton type algorithm; Figure 2B illustrates the second and subsequent iterations of the example Gerchberg-Saxton type algorithm; Figure 2C illustrates alternative second and subsequent iterations of the example Gerchberg-Saxton type algorithm; Figure 3 is a schematic of a reflective LCOS SLM; Figure 4 is a schematic plan view of a display device comprising a spatial light modulator mounted on a substrate; Figure 5 shows a schematic cross section along line X-X of Figure 4; Figure 6A shows a conventional arrangement of pads of a semiconductor device; Figure 6B shows a cross-section of a depressed pad; Figure 7 represent a first embodiment; Figure 8 represents a second embodiment; and Figure 9 represents a third embodiment. The same reference numbers will be used throughout the drawings to refer to the same or like parts. DETAILED DESCRIPTION OF EMBODIMENTS The present invention is not restricted to the embodiments described in the following but extends to the full scope of the appended claims. That is, the present invention may be embodied in different forms and should not be construed as limited to the described embodiments, which are set out for the purpose of illustration. Terms of a singular form may include plural forms unless specified otherwise. A structure described as being formed at an upper portion / lower portion of another structure or on / under the other structure should be construed as including a case where the structures contact each other and, moreover, a case where a third structure is disposed there between. In describing a time relationship - for example, when the temporal order of events is described as "after", "subsequent", "next", "before" or suchlike - the present disclosure should be taken to include continuous and non-continuous events unless otherwise specified. For example, the description should be taken to include a case which is not continuous unless wording such as "just", "immediate" or "direct" is used. Although the terms "first", "second", etc. may be used herein to describe various elements, these elements are not to be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the appended claims. Features of different embodiments may be partially or overall coupled to or combined with each other, and may be variously inter-operated with each other. Some embodiments may be carried out independently from each other, or may be carried out together in co-dependent relationship. Optical configuration Figure 1 shows an embodiment in which a computer-generated hologram is encoded on a single spatial light modulator. The computer-generated hologram is a Fourier transform of the object for reconstruction. It may therefore be said that the hologram is a Fourier domain or frequency domain or spectral domain representation of the object. In this embodiment, the spatial light modulator is a reflective liquid crystal on silicon, "LCOS", device. The hologram is encoded on the spatial light modulator and a holographic reconstruction is formed at a replay field, for example, a light receiving surface such as a screen or diffuser. A light source 110, for example a laser or laser diode, is disposed to illuminate the SLM 140 via a collimating lens 111. The collimating lens causes a generally planar wavefront of light to be incident on the SLM. In Figure 1, the direction of the wavefront is off-normal (e.g. two or three degrees away from being truly orthogonal to the plane of the transparent layer). However, in other embodiments, the generally planar wavefront is provided at normal incidence and a beam splitter arrangement is used to separate the input and output optical paths. In the embodiment shown in Figure 1, the arrangement is such that light from the light source is reflected off a mirrored rear surface of the SLM and interacts with a light-modulating layer to form an exit wavefront 112. The exit wavefront 112 is applied to optics including a Fourier transform lens 120, having its focus at a screen 125. More specifically, the Fourier transform lens 120 receives a beam of modulated light from the SLM 140 and performs a frequency-space transformation to produce a holographic reconstruction at the screen 125. Notably, in this type of holography, each pixel of the hologram contributes to the whole reconstruction. There is not a one-to-one correlation between specific points (or image pixels) on the replay field and specific light-modulating elements (or hologram pixels). In other words, modulated light exiting the light-modulating layer is distributed across the replay field. In these embodiments, the position of the holographic reconstruction in space is determined by the dioptric (focusing) power of the Fourier transform lens. In the embodiment shown in Figure 1, the Fourier transform lens is a physical lens. That is, the Fourier transform lens is an optical Fourier transform lens and the Fourier transform is performed optically. Any lens can act as a Fourier transform lens but the performance of the lens will limit the accuracy of the Fourier transform it performs. The skilled person understands how to use a lens to perform an optical Fourier transform. Hologram calculation In some embodiments, the computer-generated hologram is a Fourier transform hologram, or simply a Fourier hologram or Fourier-based hologram, in which an image is reconstructed in the far field by utilising the Fourier transforming properties of a positive lens. The Fourier hologram is calculated by Fourier transforming the desired light field in the replay plane back to the lens plane. Computer-generated Fourier holograms may be calculated using Fourier transforms. A Fourier transform hologram may be calculated using an algorithm such as the Gerchberg-Saxton algorithm. Furthermore, the Gerchberg-Saxton algorithm may be used to calculate a hologram in the Fourier domain (i.e. a Fourier transform hologram) from amplitude-only information in the spatial domain (such as a photograph). The phase information related to the object is effectively "retrieved" from the amplitude-only information in the spatial domain. In some embodiments, a computer-generated hologram is calculated from amplitude-only information using the Gerchberg-Saxton algorithm or a variation thereof. The Gerchberg Saxton algorithm considers the situation when intensity cross-sections of a light beam, lA(x, y) and lB(x, y), in the planes A and B respectively, are known and lA(x, y) and lB(x, y) are related by a single Fourier transform. With the given intensity cross-sections, an approximation to the phase distribution in the planes A and B, 4JA(x, y) and tpB(x, y) respectively, is found. The Gerchberg-Saxton algorithm finds solutions to this problem by following an iterative process. More specifically, the Gerchberg-Saxton algorithm iteratively applies spatial and spectral constraints while repeatedly transferring a data set (amplitude and phase), representative of lA(x, y) and lB(x, y), between the spatial domain and the Fourier (spectral or frequency) domain. The corresponding computer-generated hologram in the spectral domain is obtained through at least one iteration of the algorithm. The algorithm is convergent and arranged to produce a hologram representing an input image. The hologram may be an amplitude-only hologram, a phase-only hologram or a fully complex hologram. In some embodiments, a phase-only hologram is calculated using an algorithm based on the Gerchberg-Saxton algorithm such as described in British patent 2,498,170 or 2,501,112 which are hereby incorporated in their entirety by reference. However, embodiments disclosed herein describe calculating a phase-only hologram by way of example only. In these embodiments, the Gerchberg-Saxton algorithm retrieves the phase information tp [u, v] of the Fourier transform of the data set which gives rise to a known amplitude information T[x, y], wherein the amplitude information T[x, y] is representative of a target image (e.g. a photograph). Since the magnitude and phase are intrinsically combined in the Fourier transform, the transformed magnitude and phase contain useful information about the accuracy of the calculated data set. Thus, the algorithm may be used iteratively with feedback on both the amplitude and the phase information. However, in these embodiments, only the phase information tp[u, v] is used as the hologram to form a holographic representative of the target image at an image plane. The hologram is a data set (e.g. 2D array) of phase values. In other embodiments, an algorithm based on the Gerchberg-Saxton algorithm is used to calculate a fully-complex hologram. A fully-complex hologram is a hologram having a magnitude component and a phase component. The hologram is a data set (e.g. 2D array) comprising an array of complex data values wherein each complex data value comprises a magnitude component and a phase component. In some embodiments, the algorithm processes complex data and the Fourier transforms are complex Fourier transforms. Complex data may be considered as comprising (i) a real component and an imaginary component or (ii) a magnitude component and a phase component. In some embodiments, the two components of the complex data are processed differently at various stages of the algorithm. Figure 2A illustrates the first iteration of an algorithm in accordance with some embodiments for calculating a phase-only hologram. The input to the algorithm is an input image 210 comprising a 2D array of pixels or data values, wherein each pixel or data value is a magnitude, or amplitude, value. That is, each pixel or data value of the input image 210 does not have a phase component. The input image 210 may therefore be considered a magnitude-only or amplitude-only or intensity-only distribution. An example of such an input image 210 is a photograph or one frame of video comprising a temporal sequence of frames. The first iteration of the algorithm starts with a data forming step 202A comprising assigning a random phase value to each pixel of the input image, using a random phase distribution (or random phase seed) 230, to form a starting complex data set wherein each data element of the set comprising magnitude and phase. It may be said that the starting complex data set is representative of the input image in the spatial domain. First processing block 250 receives the starting complex data set and performs a complex Fourier transform to form a Fourier transformed complex data set. Second processing block 253 receives the Fourier transformed complex data set and outputs a hologram 280A. In some embodiments, the hologram 280A is a phase-only hologram. In these embodiments, second processing block 253 quantises each phase value and sets each amplitude value to unity in order to form hologram 280A. Each phase value is quantised in accordance with the phase-levels which may be represented on the pixels of the spatial light modulator which will be used to "display" the phase-only hologram. For example, if each pixel of the spatial light modulator provides 256 different phase levels, each phase value of the hologram is quantised into one phase level of the 256 possible phase levels. Hologram 280A is a phase-only Fourier hologram which is representative of an input image. In other embodiments, the hologram 280A is a fully complex hologram comprising an array of complex data values (each including an amplitude component and a phase component) derived from the received Fourier transformed complex data set. In some embodiments, second processing block 253 constrains each complex data value to one of a plurality of allowable complex modulation levels to form hologram 280A. The step of constraining may include setting each complex data value to the nearest allowable complex modulation level in the complex plane. It may be said that hologram 280A is representative of the input image in the spectral or Fourier or frequency domain. In some embodiments, the algorithm stops at this point. However, in other embodiments, the algorithm continues as represented by the dotted arrow in Figure 2A. In other words, the steps which follow the dotted arrow in Figure 2A are optional (i.e. not essential to all embodiments). Third processing block 256 receives the modified complex data set from the second processing block 253 and performs an inverse Fourier transform to form an inverse Fourier transformed complex data set. It may be said that the inverse Fourier transformed complex data set is representative of the input image in the spatial domain. Fourth processing block 259 receives the inverse Fourier transformed complex data set and extracts the distribution of magnitude values 211A and the distribution of phase values 213A. Optionally, the fourth processing block 259 assesses the distribution of magnitude values 211A. Specifically, the fourth processing block 259 may compare the distribution of magnitude values 211A of the inverse Fourier transformed complex data set with the input image 510 which is itself, of course, a distribution of magnitude values. If the difference between the distribution of magnitude values 211A and the input image 210 is sufficiently small, the fourth processing block 259 may determine that the hologram 280A is acceptable. That is, if the difference between the distribution of magnitude values 211A and the input image 210 is sufficiently small, the fourth processing block 259 may determine that the hologram 280A is a sufficiently-accurate representative of the input image 210. In some embodiments, the distribution of phase values 213A of the inverse Fourier transformed complex data set is ignored for the purpose of the comparison. It will be appreciated that any number of different methods for comparing the distribution of magnitude values 211A and the input image 210 may be employed and the present disclosure is not limited to any particular method. In some embodiments, a mean square difference is calculated and if the mean square difference is less than a threshold value, the hologram 280A is deemed acceptable. If the fourth processing block 259 determines that the hologram 280A is not acceptable, a further iteration of the algorithm may be performed. However, this comparison step is not essential and in other embodiments, the number of iterations of the algorithm performed is predetermined or preset or user-defined. Figure 2B represents a second iteration of the algorithm and any further iterations of the algorithm. The distribution of phase values 213A of the preceding iteration is fed-back through the processing blocks of the algorithm. The distribution of magnitude values 211A is rejected in favour of the distribution of magnitude values of the input image 210. In the first iteration, the data forming step 202A formed the first complex data set by combining distribution of magnitude values of the input image 210 with a random phase distribution 230. However, in the second and subsequent iterations, the data forming step 202B comprises forming a complex data set by combining (i) the distribution of phase values 213A from the previous iteration of the algorithm with (ii) the distribution of magnitude values of the input image 210. The complex data set formed by the data forming step 202B of Figure 2B is then processed in the same way described with reference to Figure 2Ato form second iteration hologram 280B. The explanation of the process is not therefore repeated here. The algorithm may stop when the second iteration hologram 280B has been calculated. However, any number of further iterations of the algorithm may be performed. It will be understood that the third processing block 256 is only required if the fourth processing block 259 is required or a further iteration is required. The output hologram 280B generally gets better with each iteration. However, in practice, a point is usually reached at which no measurable improvement is observed or the positive benefit of performing a further iteration is out-weighted by the negative effect of additional processing time. Hence, the algorithm is described as iterative and convergent. Figure 2C represents an alternative embodiment of the second and subsequent iterations. The distribution of phase values 213A of the preceding iteration is fed-back through the processing blocks of the algorithm. The distribution of magnitude values 211A is rejected in favour of an alternative distribution of magnitude values. In this alternative embodiment, the alternative distribution of magnitude values is derived from the distribution of magnitude values 211 of the previous iteration. Specifically, processing block 258 subtracts the distribution of magnitude values of the input image 210 from the distribution of magnitude values 211 of the previous iteration, scales that difference by a gain factor a and subtracts the scaled difference from the input image 210. This is expressed mathematically by the following equations, wherein the subscript text and numbers indicate the iteration number: Rn+i [x,^] = F'{exp(z>„[M,v])} = ZF{Tj-exp(iZRn[x,y])} mr i / 1 r t nrrr t\ rj = T[x,y|-a(|£„[x, v ||^7 | x.y|) where: F' is the inverse Fourier transform; F is the forward Fourier transform; R[x, y] is the complex data set output by the third processing block 256; T[x, y] is the input or target image; Z is the phase component; tp is the phase-only hologram 280B; r] is the new distribution of magnitude values 211B; and a is the gain factor. The gain factor a may be fixed or variable. In some embodiments, the gain factor a is determined based on the size and rate of the incoming target image data. In some embodiments, the gain factor a is dependent on the iteration number. In some embodiments, the gain factor a is solely function of the iteration number. The embodiment of Figure 2C is the same as that of Figure 2A and Figure 2B in all other respects. It may be said that the phase-only hologram ip(u, v) comprises a phase distribution in the frequency or Fourier domain. In some embodiments, the Fourier transform is performed using the spatial light modulator. Specifically, the hologram data is combined with second data providing optical power. That is, the data written to the spatial light modulation comprises hologram data representing the object and lens data representative of a lens. When displayed on a spatial light modulator and illuminated with light, the lens data emulates a physical lens - that is, it brings light to a focus in the same way as the corresponding physical optic. The lens data therefore provides optical, or focusing, power. In these embodiments, the physical Fourier transform lens 120 of Figure 1 may be omitted. It is known how to calculate data representative of a lens. The data representative of a lens may be referred to as a software lens. For example, a phase-only lens may be formed by calculating the phase delay caused by each point of the lens owing to its refractive index and spatially-variant optical path length. For example, the optical path length at the centre of a convex lens is greater than the optical path length at the edges of the lens. An amplitude-only lens may be formed by a Fresnel zone plate. It is also known in the art of computer-generated holography how to combine data representative of a lens with a hologram so that a Fourier transform of the hologram can be performed without the need for a physical Fourier lens. In some embodiments, lensing data is combined with the hologram by simple addition such as simple vector addition. In some embodiments, a physical lens is used in conjunction with a software lens to perform the Fourier transform. Alternatively, in other embodiments, the Fourier transform lens is omitted altogether such that the holographic reconstruction takes place in the far-field. In further embodiments, the hologram may be combined in the same way with grating data - that is, data arranged to perform the function of a grating such as image steering. Again, it is known in the field how to calculate such data. For example, a phase-only grating may be formed by modelling the phase delay caused by each point on the surface of a blazed grating. An amplitude-only grating may be simply superimposed with an amplitude-only hologram to provide angular steering of the holographic reconstruction. The second data providing lensing and / or steering may be referred to as a light processing function or light processing pattern to distinguish from the hologram data which may be referred to as an image forming function or image forming pattern. In some embodiments, the Fourier transform is performed jointly by a physical Fourier transform lens and a software lens. That is, some optical power which contributes to the Fourier transform is provided by a software lens and the rest of the optical power which contributes to the Fourier transform is provided by a physical optic or optics. In some embodiments, there is provided a real-time engine arranged to receive image data and calculate holograms in real-time using the algorithm. In some embodiments, the image data is a video comprising a sequence of image frames. In other embodiments, the holograms are precalculated, stored in computer memory and recalled as needed for display on a SLM. That is, in some embodiments, there is provided a repository of predetermined holograms. Embodiments relate to Fourier holography and Gerchberg-Saxton type algorithms by way of example only. The present disclosure is equally applicable to Fresnel holography and Fresnel holograms which may be calculated by a similar method. The present disclosure is also applicable to holograms calculated by other techniques such as those based on point cloud methods. Light modulation A spatial light modulator may be used to display the diffractive pattern including the computergenerated hologram. If the hologram is a phase-only hologram, a spatial light modulator which modulates phase is required. If the hologram is a fully-complex hologram, a spatial light modulator which modulates phase and amplitude may be used or a first spatial light modulator which modulates phase and a second spatial light modulator which modulates amplitude may be used. In some embodiments, the light-modulating elements (i.e. the pixels) of the spatial light modulator are cells containing liquid crystal. That is, in some embodiments, the spatial light modulator is a liquid crystal device in which the optically-active component is the liquid crystal. Each liquid crystal cell is configured to selectively-provide a plurality of light modulation levels. That is, each liquid crystal cell is configured at any one time to operate at one light modulation level selected from a plurality of possible light modulation levels. Each liquid crystal cell is dynamically-reconfigurable to a different light modulation level from the plurality of light modulation levels. In some embodiments, the spatial light modulator is a reflective liquid crystal on silicon (LCDS) spatial light modulator but the present disclosure is not restricted to this type of spatial light modulator. A LCOS device provides a dense array of light modulating elements, or pixels, within a small aperture (e.g. a few centimetres in width). The pixels are typically approximately 10 microns or less which results in a diffraction angle of a few degrees meaning that the optical system can be compact. It is easier to adequately illuminate the small aperture of a LCOS SLM than it is the larger aperture of other liquid crystal devices. An LCOS device is typically reflective which means that the circuitry which drives the pixels of a LCOS SLM can be buried under the reflective surface. The results in a higher aperture ratio. In other words, the pixels are closely packed meaning there is very little dead space between the pixels. This is advantageous because it reduces the optical noise in the replay field. A LCOS SLM uses a silicon backplane which has the advantage that the pixels are optically flat. This is particularly important for a phase modulating device. A suitable LCOS SLM is described below, by way of example only, with reference to Figure 3. An LCOS device is formed using a single crystal silicon substrate 302. It has a 2D array of square planar aluminium electrodes 301, spaced apart by a gap 301a, arranged on the upper surface of the substrate. Each of the electrodes 301 can be addressed via circuitry 302a buried in the substrate 302. Each of the electrodes forms a respective planar mirror. An alignment layer 303 is disposed on the array of electrodes, and a liquid crystal layer 304 is disposed on the alignment layer 303. A second alignment layer 305 is disposed on the planar transparent layer 306, e.g. of glass. A single transparent electrode 307 e.g. of ITO is disposed between the transparent layer 306 and the second alignment layer 305. Each of the square electrodes 301 defines, together with the overlying region of the transparent electrode 307 and the intervening liquid crystal material, a controllable phase-modulating element 308, often referred to as a pixel. The effective pixel area, or fill factor, is the percentage of the total pixel which is optically active, taking into account the space between pixels 301a. By control of the voltage applied to each electrode 301 with respect to the transparent electrode 307, the properties of the liquid crystal material of the respective phase modulating element may be varied, thereby to provide a variable delay to light incident thereon. The effect is to provide phase-only modulation to the wavefront, i.e. no amplitude effect occurs. The described LCOS SLM outputs spatially modulated light in reflection. Reflective LCOS SLMs have the advantage that the signal lines, gate lines and transistors are below the mirrored surface, which results in high fill factors (typically greater than 90%) and high resolutions. Another advantage of using a reflective LCOS spatial light modulator is that the liquid crystal layer can be half the thickness than would be necessary if a transmissive device were used. This greatly improves the switching speed of the liquid crystal (a key advantage for the projection of moving video images). However, the teachings of the present disclosure may equally be implemented using a transmissive LCOS SLM. Display Device A spatial light modulator, such as the LCOS SLM described in relation to Figure 3, comprises a chip or die, which may be packaged as a display device. In some embodiments, the display device is provided as part of a HUD system for use in a vehicle. The display device may be manufactured separately, as a standalone component, and then assembled into a HUD system for a particular application. Figure 4 shows a schematic top view of such a display device 400 and Figure 5 shows a cross section along line X-X of Figure 4. The display device 400 comprises a substrate 402 in the form of ceramic or alumina carrier and a spatial light modulator 404 mounted on the substrate 402. In this example, the spatial light modulator 404 is an SLM LCOS having a silicon backplane as described in relation to Figure 3. However, it will be clear to the skilled person that other spatial light modulators may take the place of the LCOS SLM of Figure 3 in the display device. In addition, other types of carrier substate or board may be used according to application requirements. A connector 406 is provided for connection to the spatial light modulator 404. In this example, the connector 406 is a flexible printed cable capable but may alternatively be a flat flex connector or a flexible printed circuit board. In particular, electrical connections 418, which are illustrated as wire bonds, extend between contact pads 414 in an electrical connection region 412 of the spatial light modulator and corresponding contact pads 416 in an electrical connection region 416 of the connector 406. The connector 406 is provided on the substrate 402 to connect the spatial light modulator 404 to at least one other part of a HUD system, such as a controller or display driver (not shown). The spatial light modulator 404 comprises a first major surface 420 including a light modulating region 410 (also called a display area or display panel) and the electrical connection region 412, and a second major surface 422 opposite the first major surface 420. The second major surface 422 of the spatial light modulator 404 is attached to a first major surface of the substrate 402 so that the display area 410 is exposed, in order to be illuminated with light. In one example, during use of the display device 404, the spatial light modulator 404 receives a computer-generated hologram from a controller via the connector 406 so as to encode the array of pixels of the spatial light modulator 400 in the display area 410. The array of pixels of the spatial light modulator 400 is then illuminated with light from a light source, such as coherent light from a laser or laser diode, such that light is incident on the spatial light modulator. The light is then modulated in accordance with the hologram and output as spatially modulated light. Although not shown in Figures 4 and 5, the substrate 402 may comprise a heat exchange portion or surface (not shown), for example extending from a second major surface of the substrate 402. The heat exchange portion of the substrate 402 may comprise an arrangement of metal heat dissipating members (e.g., aluminium fins) arranged to conduct heat to and from the spatial light modulator 404 so as to maintain it at an optimum operating temperature. As shown in Figure 5, an attachment material 430 is provided between the second major surface 422 of the spatial light modulator 404 and the first major surface of the substrate 402 in order to securely mount the spatial light modulator 404 onto the substrate 402. In particular, the attachment material 430 may comprise an adhesive paste (e.g., thermal paste) or an adhesive film (e.g., thermoplastic film) such as a so-called "die attach tape". Many attachment materials are known for use in mounting electronic components, such as chips and dies, to the surface of a carrier substrate, including pressure sensitive adhesives and other types of bonding material. Figure 6A shows a plan view of a semiconductor device comprising an active pixel area 601, a glass edge 605, an external pad array 607, a gasket seal 604, a first pad 610A and a second pad 210B. Reference is made herein to "pads" which are conductive (e.g. metallised) features for enabling electrical contact to transmit a signal or a potential or current. In some embodiments, the pads are for controlling the potential of an electrode (e.g. transparent such as ITO electrode) on the glass. The "pads" are also referred to herein as conductive elements for electrical connection. In more detail, Figure 6A shows a section of a semiconductor device. The section comprises an active pixel array 601 surrounded by a gasket seal 604. The gasket seal delineates the active pixel array 601. The active pixel array 601 may comprise a plurality of pixels such as liquid crystal pixels familiar to the person skilled in the art of semiconductor devices. There may be small gap between the outer boundary of the active pixel array 601 and the inside edge of the gasket seal 604. The gasket seal 604 may be relatively thin compared to the largest dimensions of the active pixel array 601. The active pixel array 601 and gasket seal 604 may be formed on glass having a glass edge 605. An external pad array 607 is disposed on the other side of the glass edge 605 to the active pixel array 601 and gasket seal 604. The section comprises two "pads". A first pad 610A is disposed adjacent a first corner of the active pixel array 601 furthest from the glass edge 605 and a second pad 610B is disposed adjacent a second corner of the active pixel array 601 furthest from the glass edge 605. Figure 6B shows a cross-section of a conventional pad 660 that is depressed in relation to the surrounding top surface 650. In other words, the surrounding top surface 650 is raised above the conventional pad 660. Conventionally, pads follow the foundry design rules for such features - single metal features, reinforced metal layers with vias into the depth of the silicon, height to highest internal layer with open region above to allow access. Pads are conventionally in corners or along edges, and always outside the gasket. Figure 7 shows a first embodiment of the present disclosure. Figure 7 corresponds to Figure 6A except in the structure of the pads. Figure 7 shows a plan view of a semiconductor device comprising an active pixel area 701, a glass edge 705, an external pad array 707 and a gasket seal 704 - as per Figure 6. Figure 7 further shows a first pad 710A and a second pad 710B. In this embodiment, by way of example only, the first pad 710A comprises a plurality of conductive subelements such as first conductive sub-element 712A, second conductive sub-element 712B and third conductive sub-element 712C of an array of nine conductive sub-elements. Each of the first pad 710A and second pad 710B comprise a plurality of discrete, structural features. That is, each conductive element (i.e. pad) comprises a plurality of conductive sub-elements. It may be said that each conductive element is "structured" to reflect that it is not a continuous, homogeneous element The first embodiment of Figure 7 shows a first pad 710A comprises a plurality of features in an array. In this embodiment, the first pad 701A comprises nine subelements arranged in a 3 x 3 array. However, each pad may comprise any number of sub-elements in any size or shape array. The array may be regular or irregular. The features of the pad 710A are smaller than the pad 710A itself. The features may comprise metal. The features may be said to form a group. In this embodiment, the pad 710A is outside the gasket seal 704. That is, the features are on the opposite side of the gasket seal 704 to the active pixel array 701. Conductive material is dispensed over area 714 of the second pad 710B. The conductive material may comprise a suspension of metal flakes, such as silver or nickel flakes. The metal flakes may be suspended in an epoxy. Area 714 may be radially symmetric such as circular. Area 714 may substantially cover the corresponding pad. That is, area 714 may at least partially cover or encapsule all sub-elements of the pad. It may be said that the array of sub-elements and conductive material dispensed hereon form a connection pad such as an electrical connection pad. The conductive material is applied on the top surface metal of the pad and spans the gap between it and the glass ITO electrode. In some embodiments, the semiconductor device additionally comprises a liquid crystal alignment layer (e.g. polyimide) and the conductive material additionally pierces the liquid crystal alignment material. Some embodiments provide a larger pad with metal density matched to the surrounding area. Some embodiments divide up the metal to reduce pad size. Figure 8 shows a second embodiment of the present disclosure. Figure 8 corresponds to Figure 7 except that the first pad 810A and second pad 810B are disposed inside the gasket seal 804. Figure 8 shows a plan view of a semiconductor device comprising an active pixel area 801, a glass edge 805, an external pad array 807, a first pad 810A and a second pad 810B - as per the first embodiment. Figure 8 further shows an extended gasket seal 804 that encompasses the first pad 810A and second pad 810B. In this embodiment, by way of example only, the first pad 810A comprises a plurality of conductive sub-elements such as first conductive sub-element 812A, second conductive sub-element 812B and third conductive sub-element 812C of an array of nine conductive sub-elements. The first pad 810A and second pad 810B may comprise any arrangement of conductive sub-elements as described in relation to Figure 7. Conductive material - e.g. silver or nickel flakes in suspension - is dispensed on area 814 of the second pad 810B - as per the first embodiment. In a variation, the gasket is conductive and applied over the pads to avoid the need for a separate dispense (of conductive material) at the pads. In some embodiments, the gasket has non-uniform height. For example, in some embodiments, a reflective electrode (e.g. mirror) underlies the active pixel array 701 and the pads have a depth deeper than the mirror such that the gasket is of non-uniform height where it meets the pads. A third embodiment is shown in Figure 9 in which the conductive sub-elements are indistinguishable from the active pixels (represented by diagonal hatching) disposed inside active pixel area 901 and a plurality of dummy pixels (represented by horizontal hatching). The first pad 910A and second pad are disposed inside the gasket seal 904. Figure 9 shows a plan view of a semiconductor device comprising an active pixel area 901 and an external pad array 907, a first pad 910A and a second pad - as per other embodiments. Figure 9 further shows an extended gasket seal 904 that encompasses the first pad 910A and second pad. The gasket seal 904 is delimited by an outer gasket boundary 904a and an inner gasket boundary 904b. A first pad 910A and second pad each comprise a 3 x 3 array of 9 sub-elements (each represented by a dotted fill). A line of dummy pixels is disposed in the gap between the active pixel area 901 and inner gasket boundary 904b. The first pad 910A and second pad may comprise any arrangement of conductive sub-elements as described in relation to Figure 7 and 8. Conductive material - e.g. silver or nickel flakes in suspension - is dispensed on area 914 of the second pad - as per other embodiments. It may be said that the pad is a stealth pad to reflect that is not visible on regular inspection. The different components of the semiconductor device are assigned to groups of indistinguishable sub-elements or pixels. Each dummy pixel is disconnected electrically from any other pixels which allows for the conductive material to the imprecisely dispensed. The pad may be inside or outside of the gasket seal. As per the second embodiment, the gasket may be conductive and applied over the pads so as to avoid the need for a separate dispense at the pads. In some embodiments, surface passivation layers are absent from the conductive areas because passivation layers may comprise an insulator. The semiconductor device may be a display device or spatial light modulator such as a liquid crystal on silicon spatial light modulator but the present disclosure is not limited to such devices and, instead, extends to any semiconductor device comprising at least one (connection) pad. The active pixels of the present disclosure may be light modulating pixels of a display device. The active pixels may be individually addressable in a manner that will be familiar to the person skilled in the art of display. The active pixels may be phase-modulating or amplitude and phase-modulating. The active pixel array may comprise a common electrode and an array of individual electrodes sandwiching liquid crystal. In examples in which the semiconductor device is a display device, the pixels may be arranged to display a hologram of an image or picture or suitable for displaying a hologram of a picture. Additional features Embodiments refer to an electrically-activated LCDS spatial light modulator by way of example only. The teachings of the present disclosure may equally be implemented on any spatial light modulator capable of displaying a computer-generated hologram in accordance with the present disclosure such as any electrically-activated SLMs, optically-activated SLM, digital micromirror device or microelectromechanical device, for example. In some embodiments, the light source is a laser such as a laser diode. In some embodiments, the detector is a photodetector such as a photodiode. In some embodiments, the light receiving surface is a diffuser surface or screen such as a diffuser. The holographic projection system of the present disclosure may be used to provide an improved head-up display (HUD) or head-mounted display. In some embodiments, there is provided a vehicle comprising the holographic projection system installed in the vehicle to provide a HUD. The vehicle may be an automotive vehicle such as a car, truck, van, lorry, motorcycle, train, airplane, boat, or ship. The quality of the holographic reconstruction may be affect by the so-called zero order problem which is a consequence of the diffractive nature of using a pixelated spatial light modulator. Such zero-order light can be regarded as "noise" and includes for example specularly reflected light, and other unwanted light from the SLM. In the example of Fourier holography, this "noise" is focussed at the focal point of the Fourier lens leading to a bright spot at the centre of the holographic reconstruction. The zero order light may be simply blocked out however this would mean replacing the bright spot with a dark spot. Some embodiments include an angularly selective filter to remove only the collimated rays of the zero order. Embodiments also include the method of managing the zero-order described in European patent 2,030,072, which is hereby incorporated in its entirety by reference. In some embodiments, the size (number of pixels in each direction) of the hologram is equal to the size of the spatial light modulator so that the hologram fills the spatial light modulator. That is, the hologram uses all the pixels of the spatial light modulator. In other embodiments, the hologram is smaller than the spatial light modulator. More specifically, the number of hologram pixels is less than the number of light-modulating pixels available on the spatial light modulator. In some of these other embodiments, part of the hologram (that is, a continuous subset of the pixels of the hologram) is repeated in the unused pixels. This technique may be referred to as "tiling" wherein the surface area of the spatial light modulator is divided up into a number of "tiles", each of which represents at least a subset of the hologram. Each tile is therefore of a smaller size than the spatial light modulator. In some embodiments, the technique of "tiling" is implemented to increase image quality. Specifically, some embodiments implement the technique of tiling to minimise the size of the image pixels whilst maximising the amount of signal content going into the holographic reconstruction. In some embodiments, the holographic pattern written to the spatial light modulator comprises at least one whole tile (that is, the complete hologram) and at least one fraction of a tile (that is, a continuous subset of pixels of the hologram). In embodiments, only the primary replay field is utilised and system comprises physical blocks, such as baffles, arranged to restrict the propagation of the higher order replay fields through the system. In embodiments, the holographic reconstruction is colour. In some embodiments, an approach known as spatially-separated colours, "SSC", is used to provide colour holographic reconstruction. In other embodiments, an approach known as frame sequential colour, "FSC", is used. The method of SSC uses three spatially-separated arrays of light-modulating pixels for the three single-colour holograms. An advantage of the SSC method is that the image can be very bright because all three holographic reconstructions may be formed at the same time. However, if due to space limitations, the three spatially-separated arrays of light-modulating pixels are provided on a common SLM, the quality of each single-colour image is sub-optimal because only a subset of the available light-modulating pixels is used for each colour. Accordingly, a relatively low-resolution colour image is provided. The method of FSC can use all pixels of a common spatial light modulator to display the three singlecolour holograms in sequence. The single-colour reconstructions are cycled (e.g. red, green, blue, red, green, blue, etc.) fast enough such that a human viewer perceives a polychromatic image from integration of the three single-colour images. An advantage of FSC is that the whole SLM is used for each colour. This means that the quality of the three colour images produced is optimal because all pixels of the SLM are used for each of the colour images. However, a disadvantage of the FSC method is that the brightness of the composite colour image is lower than with the SSC method - by a factor of about 3 - because each single-colour illumination event can only occur for one third of the frame time. This drawback could potentially be addressed by overdriving the lasers, or by using more powerful lasers, but this requires more power resulting in higher costs and an increase in the size of the system. Examples describe illuminating the SLM with visible light but the skilled person will understand that the light sources and SLM may equally be used to direct infrared or ultraviolet light, for example, as disclosed herein. For example, the skilled person will be aware of techniques for converting infrared and ultraviolet light into visible light for the purpose of providing the information to a user. For example, the present disclosure extends to using phosphors and / or quantum dot technology for this purpose. Some embodiments describe 2D holographic reconstructions by way of example only. In other embodiments, the holographic reconstruction is a 3D holographic reconstruction. That is, in some embodiments, each computer-generated hologram forms a 3D holographic reconstruction. The methods and processes described herein may be embodied on a computer-readable medium. The term "computer-readable medium" includes a medium arranged to store data temporarily or permanently such as random-access memory (RAM), read-only memory (ROM), buffer memory, flash memory, and cache memory. The term "computer-readable medium" shall also be taken to include any medium, or combination of multiple media, that is capable of storing instructions for execution by a machine such that the instructions, when executed by one or more processors, cause the machine to perform any one or more of the methodologies described herein, in whole or in part. The term "computer-readable medium" also encompasses cloud-based storage systems. The term "computer-readable medium" includes, but is not limited to, one or more tangible and non-transitory data repositories (e.g., data volumes) in the example form of a solid-state memory chip, an optical disc, a magnetic disc, or any suitable combination thereof. In some example embodiments, the instructions for execution may be communicated by a carrier medium. Examples of such a carrier medium include a transient medium (e.g., a propagating signal that communicates instructions). It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope of the appended claims. The present disclosure covers all modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A semiconductor device comprising a pixel area comprising a plurality of pixels, a gasket sea delimiting the pixel area and conductive element for electrical connection, characterised in that the 5 conductive element comprises a plurality of conductive sub-elements, wherein the conductiveelement is disposed within the gasket seal.

2. A semiconductor device as claimed in claim 1 wherein the conductive sub-elements are spatially separated from each other.

103. A semiconductor device as claimed in any preceding claim wherein each conductive subelement is square or rectangular.

4. A semiconductor device as claimed in any preceding claim wherein the conductive sub-15 elements are the same size and / or shape as each other.

5. A semiconductor device as claimed in any of claims 1 to 3 wherein two conductive subelements have a different size and / or shape.20 6. A semiconductor device as claimed in any preceding claim wherein the plurality ofconductive sub-elements forms a regular array such as a square or rectangular array.

7. A semiconductor device as claimed in any of claims 1 to 5 wherein the plurality of conductive sub-elements forms an irregular array.

258. A semiconductor device as claimed in any preceding claim wherein the plurality of conductive sub-elements each comprise metal.

9. A semiconductor device as claimed in any preceding claim wherein the plurality of30 conductive sub-elements is surrounded by a non-conducting material.

10. A semiconductor device as claimed in any preceding claim wherein the plurality of conductive sub-elements is arranged to have conductive material dispensed thereon.26 03 2511. A semiconductor device as claimed in claim 10 wherein the conductive material comprises metal flakes, such as silver or nickel flakes, suspended in epoxy.

12. A semiconductor device as claimed in claim 10 or 11, wherein the conductive material is 5 disposed within the gasket seal.

13. A semiconductor device as claimed in claim 10 or 11, wherein the conductive material partially or completely forms the gasket seal.10 14. A semiconductor device as claimed in any of claims 1 to 11 wherein the semiconductordevice comprises an array of cells, wherein a first group of cells respectively correspond to the plurality of pixels, a second group of cells correspond to isolated pixels and a third group of cells correspond to the conductive element, wherein cells of the second group are electrically isolated from all other cells.1515. A semiconductor device as claimed in claim 14 wherein cells of the first group of cells are electrically connected to a common electrode, optionally, wherein the common electrode is reflective.20 16. A semiconductor device as claimed in claim 14 or 15 wherein the gasket seal is conductiveand applied over the third group of cells.

17. A semiconductor device as claimed in any of claims 14 to 16 wherein a subset of isolated pixels is disposed between the gasket seal and the pixel area.2518. A semiconductor device as claimed in any preceding claim wherein the pixels of the pixel area are fillable with liquid crystal.

19. A semiconductor device as claimed in any preceding claim wherein the conductive element 30 is electrically isolated and / or spatially separated from the pixel area.

20. A semiconductor device as claimed in any preceding claim wherein the gasket seal is electrically isolated from the pixel area.

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