DE102007015502A1 - CMP system with an eddy current sensor of lower height - Google Patents

Abstract

By providing an eddy current sensor element in a polishing system at a lower height level in conjunction with a corresponding optical end point detection system, standard polishing pads can be used, thereby improving the life of the polishing pad and increasing machine utilization.

Description

Field of the present disclosure

in the In general, the subject matter disclosed herein relates to the field the manufacture of integrated circuits and in particular CMP (chemical mechanical) polishing process equipment used for manufacturing modern metallization structures are used, such as so-called Damascene structures containing metal trenches and vias be prepared in an insulating layer, wherein below the contact bushings and the trenches be filled with a metal and the structure is leveled by applying the excess metal a polishing process is removed.

Description of the state of the technology

typically, requires the manufacture of modern integrated circuits one size Number of individual process steps, with a typical process sequence the deposition of conductive, semiconductive or insulating layers on a suitable substrate. After separating the appropriate Layer, component structural elements are made by the corresponding Layer is structured by known means, such as photolithography and etching. Consequently, by patterning a deposited layer, a certain topography generated, which in turn the deposition and influences the structuring of subsequent layers. As the most modern integrated circuits producing a multitude of successive Require layers, it is common the surface periodically leveling the substrate so as to provide well-defined conditions for the Depositing and structuring of subsequent material layers too create. This applies in particular to so-called metallization layers, in which metal compound structures are made to the individual device features, such as transistors, capacitors, resistors and the like so as to electrically connect through the Circuit element required functional behavior to achieve.

In In this regard, CMP has been widely used Process technology to detect "irregularities" in substrate topography, which are caused by preceding processes to reduce to improve conditions for a subsequent process, such as to produce the photolithography, and the like. The polishing process itself causes mechanical damage on the polished surface, but in a very small amount Area, d. H. at the atomic level, depending on the process conditions. Also own CMP processes a variety of side effects that need to be considered in order to process to be applicable to the manufacture of state-of-the-art semiconductor device required are.

For example was in the younger Past the so-called damascene or insertion technique preferred method in the production of metallization layers, wherein a dielectric layer is deposited and patterned that these trenches and contact holes who receives subsequently with suitable metals, such as aluminum, copper, copper alloys, Silver, tungsten and the like are filled. Because the process depositing the metal as a "whole-area" deposition process on the basis be performed by, for example, electrochemical deposition may require the appropriate pattern of dielectric material possibly a significant amount of excess material, around narrow openings and wide areas or ditches to fill reliably in a common process. The excess metal is then removed and the resulting surface is leveled by running a process sequence in which one or more mechanical polishing processes are involved, wherein Also included is a chemical component. The chemical-mechanical Polishing (CMP) has proven to be a reliable technique the excess metal to level and level the resulting surface so that metal trenches and Vias stay behind which are electrically isolated from each other, as by the corresponding Circuit arrangement is required. Chemistry-mechanical polishing requires that the substrates are attached to a carrier be attached, a so-called polishing head, so that the einbennende substrate surface is free and can be pressed against a polishing pad. The polishing head and the polishing pad are moved relative to each other, usually the Polishing head and the polishing pad individually set in motion become. Typically, the head and the polishing pad are against each other set in rotation, the relative movement is controlled so that locally a desired one Material removal is achieved. While The polishing process will typically be an abrasive that includes chemically reactive agent and possibly contains abrasive particles, the surface supplied to the polishing pad.

A problem with the chemical mechanical polishing of substrates is that very different removal rates occur for different materials, such as a metal and a dielectric material, from which the excess metal is to be removed. For example, in the polishing state in which the dielectric material and the metal are treated simultaneously, ie, after the majority of the metal is already removed, the removal rate for the metal will be greater than the Ab carrying rate for the dielectric material. This may be desirable because the entire metal should be reliably removed from all insulating surfaces to ensure the required electrical insulation. On the other hand, significant metal removal from the trenches and vias may result in trenches and vias that have increased electrical resistance due to the reduced cross-sectional area. Further, the local removal rate may be significantly dependent on the local structure, ie, the local pattern density, which may result in a locally varying degree of erosion of the dielectric material in the final phase of the polishing process. To illustrate a typical damascene process more clearly, is now on the 1a to 1e directed.

1a to 1c show schematically cross-sectional views of a semiconductor structure 100 during various phases in the fabrication of a metallization layer according to a typical Damascus process sequence.

1a shows the semiconductor structure 100 with a substrate 101 which carries circuit elements (not shown) and an insulating cover layer on which metal lines are to be made. A structured dielectric layer 102 is above the substrate 101 formed and contains openings, for example in the form of narrow trenches 103 and wide trenches 104 , The dielectric layer 102 also contains densely packed openings 109 , The openings for the trenches 103 . 109 and 104 are patterned according to the design rules to produce metal lines having the required electrical properties in terms of their performance and conductivity. For example, the ditch 104 designed as a so-called wide line to allow a low electrical resistance. The deposition of the dielectric material 102 and the structuring of the trenches 103 . 109 and 104 is accomplished by well known deposition, etching and photolithography techniques.

1b schematically shows the semiconductor structure 100 after depositing a metal layer 105 For example, a copper layer when modern integrated circuits are considered. How out 1b it can be seen, the topography of the metal layer 105 through the underlying pattern of the dielectric layer 102 affected. The metal layer 105 is deposited by chemical vapor deposition, sputter deposition, or typically copper, preferably by electroplating, whereby a previous sputter deposition process is performed for a corresponding copper seed layer. Although the exact shape of the surface profile 105 depends on the deposition method used, in principle, a surface shape is obtained, as in 1b is shown.

After that, the semiconductor structure becomes 100 subjected to the chemical-mechanical polishing, in which, as previously mentioned, the abrasive and the polishing pad are chosen so that the excess metal in the metal layer 105 optimally removed. During chemical mechanical polishing, the excess metal is removed and eventually becomes surface areas 120 of the dielectric material 102 wherein it is necessary to continue the polishing process according to a certain post-polishing time to ensure the removal of the metal from all the insulating surfaces so as to avoid an electrical short between adjacent metal lines. As previously stated, the rate of removal of the dielectric material may be significantly different than that of the metal such that when repolishing the semiconductor structure 100 the copper in the trenches 103 . 109 and 104 is removed.

1c schematically shows a typical result of a chemical mechanical polishing of in 1b shown structure. How out 1c can be seen are during the repolishing of the semiconductor structure 100 different materials polished simultaneously with different removal rates. The rate of removal also depends to some extent on the underlying pattern. For example, metal removal during post-polishing, also referred to as notching, as well as erosion of the dielectric material, also referred to as erosion, is significantly affected by the nature of the pattern to be polished. In 1c are the notch and erosion at the wide trenches 104 like this through 107 and 106 is relatively moderate, whereas on the narrow lines 103 the notch 107 and erosion 106 are clearly pronounced. In order to achieve required electrical conductivity, the circuit designers must take into account a degree of indentation and erosion, which may not be compatible with the construction of advanced devices.

Therefore, complex control strategies are used in modern CMP plants to generate on-site, ie, in situ, measurement data for estimating a suitable end point of the polishing process and / or to control the uniformity of the polishing process. For example, the layer thickness can be monitored at various locations on the substrate in order to determine the local removal rate during the process and / or to determine a suitable time for terminating the process. For this purpose, optical measuring methods, such as spectroscopic ellipsometry or other Reflektivitätsmessverfahren be used. Since the optical probing of the substrate surface is difficult due to the nature of the polishing process, a great deal of effort has to be expended to equip suitable CMP systems with optical measurement capabilities. For this purpose, suitably designed polishing pads and polishing pads have been developed which allow optical access to the substrate surface during polishing. This can be accomplished by providing corresponding transparent windows in the polishing pad. Therefore, appropriate optical measurement data can be obtained for a variety of dielectric materials and very thin metal layers during polishing, allowing efficient control strategies and endpoint detection strategies. For moderately thick initial metal layers, such as typically found in the formation of metallization layers, as previously shown, improved process control strategies may also be important during any phase of the polishing process with initially thick metal layers that are not efficiently realized by currently available optical systems ,

For this reason, other in-situ measurement strategies have been proposed, such as sensors based on inductive coupling. In this case, eddy currents are generated in the metal layer, which depend on the layer thickness. The response of a sensor coil to eddy currents can then be used to evaluate the local thickness of the layer. Corresponding sensor systems can be very efficient in situations previously described with respect to the 1a to 1c described because the metal removal can be monitored by the changing amount of induced eddy currents. Thus, advanced control schemes based on optical and inductive systems may be employed, and in advanced CMP systems both optical process control and inductive process control may be contemporaneous. For example, corresponding inductive sensor regions are disposed close to the substrate surface within the polishing window of specially designed polishing pads in which the corresponding distance or "air gap" between the substrate surface and the sensor region is reduced by providing a thinned material region in the optically transparent pad window efficient optical and inductive coupling during demanding polishing processes.

In advanced CMP techniques are the operating costs for appropriate Investment is an important factor, as the CMP costs have clearly increased in recent years have risen. The supply and handling of abrasives, Polishing pads, conditioners, cleaning units and the like is extremely expensive. Thus, appropriate process and Control strategies in which special and therefore expensive consumables are required, such as polishing pads, as described above, in terms of consumption of consumables and the like improve as these factors add up to the increased production costs Reason of frequent Change of consumables, lower plant utilization and availability and the like contribute. In the case described above the specially designed pillows are very expensive and show a reduced Lifetime due to a replacement of the window and / or a deterioration of the thin material area in the cushion window.

in view of The above problems are aimed at one or more of the operation Modern polishing systems involved avoid problems or at least to reduce in impact.

Overview of the present disclosure

in the In general, the subject matter disclosed herein relates to CMP facilities and related Components, such as polishing pads, sensor components, and the like, the on-site or in-situ monitoring enable the polishing process wherein at least one inductive sensor is provided, which is a signal that is related to the amount of conductive material stands, which is formed on a surface to be treated. As explained above, are typically the optical in very modern CMP systems Process control and process control based on inductive sensor concepts, for example provided simultaneously using the eddy current principle thus the controllability and flexibility of the corresponding CMP plants to improve. In these conventional CMP plants become technically advanced Polishing pads with extra thin cushion windows used both the efficient optical coupling as well to enable efficient inductive coupling. Due to the demanding Structure of the corresponding polishing pads result in significantly increased operating costs, since in particular the shorter life of the corresponding window areas a more common one Replacement of a polishing pad required. In visual Embodiments disclosed herein a corresponding inductive sensor provided in the appropriate Way is designed so that the use of cushion windows with increased Thickness and / or standard polishing pads, as typically in optical endpoint recognition systems and CMP systems without additional Eddy current sensor elements can be used, thereby the entire life of the polishing pad is increased.

In An illustrative embodiment disclosed herein includes a polishing system a polishing pad having a surface that is formed Undercushion and an upper cushion to absorb, which is a polishing surface and a lower surface in contact with the lower pad, wherein the lower pad a first opening which is covered by a portion of the upper pad. Furthermore, the polishing system includes an inductive sensor with a feeler surface that is positioned so that it extends from the surface of the polishing pad in the first opening extends, wherein the sensor surface on a height level is smaller than a height level of the lower surface of the upper cushion.

A Illustrative polishing equipment disclosed herein comprises a Polishing plate with a surface, for receiving a polishing pad having a substantially uniform thickness is trained. Furthermore, the polishing system includes an inductive Sensor with a sensor surface, the is positioned so that it extends from the surface of the plate and the polishing pad supports.

In Another illustrative embodiment includes a polishing pad for one CMP plant a base material, which is adapted to be mounted on a polishing plate, wherein bounded the base material laterally Contains areas, in which a magnetic material is enclosed. The polishing pad further comprises a surface for polishing a substrate.

Brief description of the drawings

Further Aspects of the present disclosure are defined in the appended claims and go more clearly from the following detailed description when studying with reference to the accompanying drawings becomes, in which:

1a to 1c schematically show cross-sectional views of a semiconductor device during various manufacturing stages in the formation of a modern metallization structure using a CMP process for removing excess material;

2a schematically shows a plan view of a CMP system with an inductive sensor according to illustrative embodiments;

2 B and 2c schematic cross-sectional views of a part of the CMP system off 2a according to still further illustrative embodiments, in which a sensor surface of an inductive sensor element is positioned at a height that is lower than modern conventional CMP systems having optical and inductive sensor components;

2d schematically shows a cross-sectional view of a CMP system having an optical detection system in conjunction with an inductive sensor element, wherein a corresponding window of the polishing plate according to illustrative embodiments is provided; and

3a and 3b schematically show cross-sectional views of a polishing pad with a magnetic material contained therein according to still further illustrative embodiments.

Detailed description

It It should be noted that although the present disclosure is related to to the embodiments as described in the following detailed description As shown in the drawings, the detailed description as well as the drawings do not intend the object on the specific disclosed embodiments restrict but the described embodiments merely exemplify various aspects of the present invention Revelation whose scope defined by the appended claims is.

The subject matter disclosed herein addresses the issue of increased operating costs and lower plant availability of modern CMP plants or other types of polishing facilities where advanced on-site process monitoring based on inductive sensor concepts is required. As previously explained, complex polishing processes to remove excess material and planarize the surface topography may require precise monitoring of the rate of removal even prior to a final phase of polishing, thereby reliably controlling the corresponding polishing process. For example, during the removal of excess copper, reliable monitoring of the remaining portion of copper material is an important aspect, even in the initial phase or an intermediate process phase, to allow high removal rates without introducing undesirable process nonuniformities. During a corresponding polishing process, an optical detection system may be less efficient because the corresponding reflectivity does not provide sufficient information about the amount of material remaining, as the initial surface topography is increasingly leveled, causing a very uniform scattering behavior of the corresponding surface, while the remaining amount of Metal no determination of information with regard to the remaining layer thickness allows. In this case, Kings efficient non-contact measuring methods, for example, based on inductive principles by generating eddy currents in the metal surface to be treated to estimate the remaining material thickness, the corresponding measurement information can also be used to determine a suitable endpoint of a high removal rate polishing phase, for example to proceed to a subsequent phase with a lower removal rate, so that the corresponding dielectric surface is substantially completely exposed, and thus to electrically isolate the respective metal areas contained therein. During this polishing phase, optical endpoint detection methods or process monitoring methods may be used efficiently, possibly in conjunction with the inductive sensor components, to achieve substantially uniform material removal with efficient exposure of the corresponding dielectric surface areas, without substantially eroding the dielectric material and Indentification of exposed metal areas is contributed. Thus, in particular, the combination of optical measuring strategies and inductive sensor concepts can be extremely advantageous in corresponding manufacturing sequences in which highly conductive metals, such as copper, copper alloys, silver, tungsten, and the like, are formed over a patterned dielectric material whose surface topography in a subsequent step on the Basis of a polishing process is leveling. In addition to a high process quality of corresponding process steps, however, other factors during the complex manufacturing process for the production of microstructure devices of comparable importance, such as the plant utilization, the plant availability, the operating costs of appropriate process equipment, and the like, as in addition to a high production yield and the total throughput for a given facility determines the profitability of the entire manufacturing sequence. In particular, since polishing processes in the form of chemical mechanical polishing or electrochemical polishing and the like have become significantly more important in the fabrication of complex semiconductor devices, a significant reduction in the operating costs of polishing processes in conjunction with an improvement in equipment availability can contribute to a reduction in overall manufacturing costs.

In Illustratively, embodiments disclosed herein will be corresponding provided inductive sensor systems in modern polishing plants, being extremely demanding and therefore expensive and sensitive polishing pads are not required are, as in a variety of modern conventional CMP systems the case is, for example, in the polishing plant "Reflexion LK", by Applied Materials Inc. available is. In some illustrative embodiments, a standard polishing pad is used with a standard cushion window, that for the optical process control is used, the corresponding sensor arrangement in a suitable manner to the respective Thickness of the standard polishing pad is adjusted. In other illustrative embodiments, the corresponding altitude position or the height level a sensor surface of a inductive sensor appropriately positioned in an adjustable manner so be that increased flexibility in choosing a suitable pillow configuration in the most modern Po lieranlagen possible is. Consequently, you can in modern polishing plants corresponding optical measuring systems and inductive sensor systems can be combined without having specially designed Polishing pads are required.

It should be noted that the subject matter disclosed herein Polishing equipment, such as electrochemical mechanical polishing equipment and The same can be applied to the production of very complex Semiconductor devices can be used, such as CPU's, memory chips, and the like, in state-of-the-art metallization structures for electrical connection of circuit elements, such as transistors, and the like, the critical dimensions of about 50 nm and much less exhibit. However, you can the principles of the subject matter disclosed herein also apply to situations be applied, in which the polishing equipment at least temporarily for removal of conductive materials used by corresponding substrate surfaces wherein the provision of an inductive sensor system in combination with a less critical polishing pad can provide improved plant flexibility, especially when the corresponding inductive sensor system in conjunction is used with a corresponding optical detection system. So far as this is not the case in the description or the appended claims explicitly stated otherwise, the subject matter disclosed herein should be not as on polishing processes for making copper-based Metallization be considered limited.

Related to the 2a to 2d and 3a Now, further illustrative embodiments will be described in more detail.

2a schematically shows a plan view of a polishing plant 200 representing a CMP plant, an electro-CMP plant or other polishing plant or the like. The polishing plant 200 includes a frame or a frame 210 formed, a polishing plate 220 , a polishing head 230 and a pillow conditioner 260 such as corresponding mechanical, electrical and other components for operating the corresponding components 220 . 230 . 260 take. It should be noted that the plate 220 is rotatably supported by respective drive assemblies (not shown), which are formed, a controllable rotation of the plate 220 according to the process parameters. Similarly, the polishing head 230 formed in combination with suitable mechanical, electrical, hydraulic, pneumatic and other compo nents to receive a corresponding substrate, such as a semiconductor substrate with 200 mm diameter, 300 mm or 450 mm in diameter or other suitable size and the substrate relative to the polishing plate 220 in accordance with the specified process parameters in rotation, wherein a special contact pressure force is exerted on the substrate to a desired interaction with a corresponding polishing pad (in 2a not shown) in conjunction with a suitable abrasive substance, such as a chemical component, an electrolyte, and the like. Similarly, the pillow conditioner 260 connected to a suitable drive assembly so as to provide the desired positioning of a corresponding conditioning surface (not shown) over the polishing pad 220 whereby efficient processing of the corresponding pad surface is possible to maintain substantially uniform process conditions in processing a variety of substrates.

The polishing plant 200 further includes a sensor area 221 in the polishing plate 220 is formed, in which at least one inductive sensor 240 with a suitable feeler surface 241 is provided, which is positioned close to a corresponding surface of a substrate during the operation of the polishing plant 200 to treat. In some illustrative embodiments, the sensor area is 221 designed so that an optical access to a corresponding substrate surface during operation of the plant 200 is possible, the sensor area 221 has a suitably designed surface area in the respective polishing pad that is substantially transparent to a respective wavelength range, as described in more detail below.

During operation of the polishing plant 200 becomes a substrate in the polishing head 230 based on well-known components, such as disk robots, and the like, wherein the polishing head 230 itself may be designed to handle the respective substrate handling and transport activities within the polishing plant 200 perform. The substrate in the polishing head 230 has been invited, is brought into a corresponding operating position and the respective relative movement between the polishing plate 220 and the polishing head 230 can be achieved on the basis of appropriate rotational movements of these components, wherein before and / or during the relative movement of a suitable abrasive substance is supplied, which may contain a chemical agent or other compo nent to improve the Gesamtabtragsrate, or for improved surface conditions during the corresponding polishing process provides. The pillow conditioner 260 may be in constant or temporary contact with the corresponding polishing surface to "condition" the surface structure 200 the sensor area passes over 221 the substrate surface, the sensor surface 241 Causes eddy currents in the substrate to be treated if a sufficiently conductive material or magnetic material is provided thereon. For example, the inductive sensor includes 240 an excitation coil and a sense coil (not shown), both with the probe surface 241 The exciter coil generates a corresponding varying magnetic field that causes the eddy currents in a conductive material that is near the sensing surface 241 and is provided in particular on the surface of the substrate to be treated. Thus, the electrical response of the sensing coil can characterize the amount of conductive material that is proximate to the sensing surface 241 whereby an efficient means is provided to evaluate the corresponding polishing process in a very dynamic manner. In other cases, the sensor includes 240 a single coil or a system of coils connected to the sensor surface 241 are coupled, wherein the total inductance of the corresponding system is influenced by the amount of the conductive material and thus by the eddy currents induced therein. Consequently, when driving the respective coil with a suitable AC signal, the response of the coil may also be indicative of the amount of conductive material and hence the current state of the polishing process.

As can be seen, during operation of the polishing plant 200 the corresponding surface of a polishing pad with the substrate to be treated and the pad conditioner 260 Interaction, whereby the overall life of the corresponding polishing pad is limited. Similarly, the surface of the sensor area 221 with the substrate surface and the pad conditioner 260 come into contact, reducing the status of the particular material that the sensor area 221 covered, and which may also be referred to as a window, is significantly influenced, as described in more detail below. In modern applications, the corresponding window is made of a substantially transparent material with a different configuration in the ver therefore, the window may be made less permanent than the remaining surface area of the polishing pad.

In conventional devices, a corresponding cushion window is provided with an even reduced material thickness to reduce the corresponding gap between a sensing surface and the substrate to be treated. In this case, even more rapid wear of the corresponding window area is observed, thereby extending the overall life of the polishing pad, although the remaining polishing surfaces continue to be in a functional condition. For this reason, the feeler surface 241 as described herein, suitably positioned to provide greater material thickness between the surface 241 and the respective substrate, thereby reducing the risk of material detachment or premature wear of the window material.

2 B shows schematically a cross-sectional view of a part of the plate 220 according to illustrative embodiments. The polishing plate 220 has trained on a polishing pad 250 with a polishing surface 253 to treat a substrate surface, as previously explained. In the illustrated embodiment, the polishing pad is 250 from a sub-pillow 251 that on a surface of the polishing plate 220 is provided, and an upper pillow 252 built, that the polishing surface 253 and a lower surface 254 owns that with the subpad 251 is in contact. In the embodiment shown, the subpad comprises 251 a corresponding opening 251 in which the respective sensor surface 241 inductive sensor 240 is to introduce. In the embodiment shown, the sensor 240 or at least the feeler surface 241 with a corresponding height adjustment unit 245 connected, which is formed, the height level of the sensor surface 241 adjust or vary in a suitable manner according to the respective process and component requirements. The height adjustment unit 245 may be configured to allow the corresponding vertical movement based on suitable components, such as electric motors, pneumatic components, hydraulic components, or combinations thereof, as known in the art. For example, an electric motor may be connected to a threaded member to adjust the rotational motion of the electric motor to a corresponding vertical motion for adjusting the height position of the feeler surface 241 convert. In one illustrative embodiment, the height adjustment unit is 245 designed so that the positioning of the sensor surface 241 at a height or at a height level above and below the lower surface 254 is possible, thereby creating the possibility of a variety of different types of upper cushion 252 with a respective window area 252W to use, wherein a corresponding material thickness may vary depending on the type of pad used. For example, the top cushion 252 represent a modern polishing pad, as used in advanced polishing equipment, the window area 252W is constructed of a substantially transparent material to thereby optically probing a substrate surface during operation of the system 200 to allow, as described above. In this case, the feeler surface becomes 241 close to the material or in contact with the window area 252W arranged, thereby operating the plant 200 according to conventional strategies is possible. If a significantly larger thickness of the window area 252W apply to z. For example, the material separation or the material degradation in the window area 252W to decrease, the sensor surface becomes 251 suitably positioned so that the correspondingly greater material thickness is taken into account.

2c shows schematically a cross-sectional view of the polishing plate 220 and the inductive sensor element 240 according to further illustrative embodiments. The upper pillow 252 has a substantially uniform thickness 252T over the entire polishing plate 220 away, so that too the window area 252W provided with a corresponding material thickness. The upper pillow 252 may in this case be provided as a standard polishing pad designed for modern polishing equipment containing optical detection systems, such as the "Reflection" or "Mirra" equipment available from Applied Materials Inc. The upper cushion 252 may be constructed from a microporous polymeric material, such as a polyurethane material having a suitable surface finish, in the polishing surface 253 is formed so as to produce a desired polishing effect in conjunction with a suitable abrasive material. In some illustrative embodiments, the window area becomes 252W as a transparent polyurethane material, to allow for an optical endpoint technique, as previously described, while in other illustrative embodiments, the window area 252W made of the same material as the remaining part of the pillow 252 is constructed when an optical access is not required. Thus, the pillow can 252 be provided with a suitable thickness, for example 80 mils and the like, without a material reduction in the sensor area 221 is necessary, which otherwise leads to premature failure of the polishing pad 252 could lead. Thus, the feeler surface becomes 241 positioned at a suitable height level, which is substantially the height level of the lower surface 254 corresponds, whereby additionally the window area 252W which may further contribute to better uniform process conditions.

During operation of the polishing plant 200 with the configuration of the inductive sensor 240 , as in the example 2 B and 2c is shown, a signal is generated on the basis of an AC signal, which is inductively coupled into the respective substrate surface, that is, in a conductive material provided thereon or therein, the corresponding signal through a suitable control unit 246 is evaluated. The respective gap between the sensor surface 241 and a corresponding substrate surface, substantially the thickness 252T in the in 2c shown embodiment or a corresponding thickness of the window area 252W as he is in 2 B can be considered in the evaluation of a corresponding transmitter signal by using suitable calibration methods, including providing a predefined amount of material over the window area 252 may belong to generate suitable reference data. Furthermore, corresponding compensation data can be determined which can take into account temperature-dependent effects and total pad wear, ie a reduced thickness 252T which can vary when processing a variety of substrates. Consequently, even for an increased gap width between the sensor surface 241 and the polishing surface 254 compared to conventional designs in which the window area 252 a significantly lower material thickness, a reliable sensor signal can be obtained, whereby modern process control strategies are possible, in addition to a significantly greater overall life of the polishing pad 252 due to the greater layer thickness and the low probability of material detachment at the window area 252W is reached.

Furthermore, in the reference to 2 B described embodiment of modern polishing pad 252 be used when a greater signal strength is required, ie a greater inductive coupling of the substrate to be treated, for example, if conductive material layers are to be treated with a small thickness, which otherwise show no pronounced response to the magnetic field. In other cases, the plant can be efficiently reconfigured using standard polishing pads with the appropriate height of the sensor element and thus the probe surface 242 suitable based on the height adjustment unit 245 can be adjusted. In some illustrative embodiments, the height adjustment unit becomes 245 according to a respective wear of the polishing pad 252 operated, regardless of whether a standard pillow, as it is in about 2 is shown, or a modern pillow, as it is in 2 B is shown, thereby creating the possibility of the resulting gap between the sensor surface 241 and the polishing surface 253 essentially to maintain. This can be z. B. be accomplished on the basis of a corresponding reference substrate that regularly in the system 200 is processed, with a deviation from the expected signal by appropriately controlling the height adjustment unit 245 is compensated so that a substantial match between the measured signal and the expected signal is achieved.

2d schematically shows the polishing system 200 according to another illustrative embodiment, wherein an optical measuring system 270 under the sensor area 221 is arranged, ie a corresponding opening in the polishing plate 220 is provided. The optical system 270 is on a holding element 271 attached, which in turn mechanically with a drive assembly 222 is provided, which is formed, the polishing plate 220 to turn. The optical system 270 includes a light source 272 , which is designed to emit a light beam and this on the surface of a substrate 231 to be addressed, which is currently being edited. Furthermore, the optical system includes 270 a detector 273 which is formed and arranged from the surface of the substrate 231 to receive reflected light beam. The respective light beams may pass through a substantially transparent material in the window area 252W is intended to be received, as previously explained. The light source 272 and the detector 273 are with a control unit 274 coupled, which is formed by the sensor 273 to evaluate received signal and, if necessary, the light source 272 to drive in a suitable manner. Furthermore, in the embodiment shown, the control unit 274 and the control unit 246 with a plant-internal control unit 201 coupled, which is formed, corresponding components of the system 200 , about a drive unit 223 for driving the polishing head 230 and a corresponding drive unit 223 for driving the polishing plate 220 to control.

When operating the system 200 as they are in 2d Consequently, optical signals are associated with signals coming from the sensor 240 are generated to provide improved test control and / or endpoint detection during processing of the substrate 231 to enable. In the in 2d the embodiment shown is the window area 252W substantially the same thickness as the remainder of the polishing pad 252 provided as previously explained, thereby increasing the life of the polishing pad 252 and increased plant availability and utilization due to the reduced number of outages Changes of polishing pads and maintenance activities can be achieved.

3a schematically shows a cross-sectional view of a part of a polishing plate 320 with a polishing pad mounted on it 350 that made a subpad 351 and an upper pillow 352 is constructed, as previously explained. For example, the upper cushion has 352 a substantially uniform thickness, as previously described, while the subpad 351 a corresponding opening 351 having. Furthermore, an inductive sensor extends 341 in the opening 351a , The upper pillow 352 includes an area 352w containing therein a magnetic material to the magnetic conductivity of the area 252W increase, creating a corresponding gap between the sensor 340 ie a sensor surface 341 , and the polishing surface 353 is reduced. The magnetic material called as 252m can be constructed of small particles with soft magnetic materials, such as ferrite materials, and the like, which has a high electrical resistance, so as to reduce the risk of generating eddy currents in the area 252W to reduce. The corresponding small particles may be provided in the form of a suitable metal powder or the like, and may be incorporated during the corresponding manufacturing process, with a suitable piece of material then being in the region 352w is used, as is typically done when a substantially transparent material in the area 352w is provided. In other illustrative embodiments, the upper cushion becomes 352 made on the basis of conventional techniques and the magnetic material 352m is provided locally, creating corresponding areas 352w be defined in a substantially homogeneous material.

3b schematically shows the polishing pad 350 when it's on the polishing plate 320 is mounted, according to further illustrative embodiments, in which a magnetic material 351m additionally or alternatively in a corresponding area 351W of the subcushion 351 is provided. Thus, the subpad 352 with an opening in the area 351W be provided so that the corresponding inductive sensor 340 is formed such that the sensor surface 341 with the area 351W is in contact with the magnetic material 351m the desired efficient magnetic coupling through the subpad 351 to the upper pillow 352 supplies. In this case, the mechanical strength of the sub-pad 351 due to the lack of a corresponding opening for the inductive sensor 341 is required, improved. If a corresponding opening is provided for optical access, the opening may be designed to meet the requirements of the optical measuring system while the sensor surface 341 of the material with the magnetic substance 351m is covered. It should be noted that in the 3a and 3b can be suitably combined in order to increase the magnetic coupling to a substrate surface to be treated. For example, in some illustrative embodiments, the magnetic material 352m be provided in a laterally limited area whose lateral dimension is smaller compared to the sensor surface 341 , whereby the corresponding field lines are "focused", which may be advantageous for obtaining a scanning region with smaller lateral dimensions.

It Thus, the present invention provides an improved sensor configuration for sensor systems in polishing systems based on an inductive coupling, such as Basis of eddy currents ready in order to avoid the need of applying modern and therefore expensive To avoid or reduce polishing pads, the lower one Have material thickness at the respective windows of the pillows. To this Purpose can be the height level an inductive sensor surface in comparison be reduced to conventional designs or in one adjustable way to be provided with it the possibility to create standard polishing pads to apply, which is a significantly higher Lifespan compared to state-of-the-art polishing cushions with windows having reduced material thickness. Consequently, the Total cost of ownership reduced and plant availability can be increased which contributed to an increased overall throughput becomes.

Further Modifications and variations of the present invention will become for the One skilled in the art in light of this description. Therefore, this is Description as merely illustrative and intended for the purpose, the expert the general manner of carrying out the present invention to convey. Of course are the forms of the invention shown and described herein as the present preferred embodiments consider.

Claims (19)

A polishing apparatus comprising: a polishing pad having a surface configured to receive a subpad and an upper pad, the upper pad having a polishing surface and a lower surface in contact with the subpad, and wherein the sub pad has a first opening that is from a part of the upper cushion is covered; and an inductive sensor located in the first opening , wherein the inductive sensor has a sensing surface positioned at a height position that is less than a height position of the lower surface of the upper pad. The polishing plant according to claim 1, wherein the upper cushion has a substantially transparent window. The polishing plant according to claim 2, wherein the window above the first opening is disposed in the subpad. The polishing plant according to claim 2, wherein the window is above a second opening, which is formed in the lower pad, is arranged. The polishing plant of claim 1, wherein the sensor surface is substantially flush to a surface of the sub-pad that is in contact with the upper pad. The polishing plant according to claim 1, further comprising a control unit which is coupled to the inductive sensor to a signal in response to the presence of a conductive material over the top To get pillows. The polishing plant according to claim 2, further comprising an optical Measuring system includes the optical with the window for optical probing a surface area a substrate disposed on the upper pad, coupled is. The polishing plant according to claim 1, wherein the upper cushion has a magnetic material at a region above the Sensor surface arranged is. The polishing plant according to claim 1, further comprising a height adjustment unit which is coupled to the sensor surface and is formed, a height to vary the feeler surface. A polishing plant according to claim 1, wherein a thickness of the upper pillow over the polishing pad is substantially uniform. Polishing plant with: a polishing plate with a Surface, formed, a polishing pad having a substantially uniform thickness record; and an inductive sensor with a sensor surface, the is positioned so that these are different from the surface of the Plate extends and supports the polishing pad. The polishing plant of claim 11, further comprising a subpad provided under the polishing pad, wherein the lower pad at least one opening has to receive the sensor surface. The polishing plant according to claim 11, wherein the feeler surface of a window portion of the polishing pad is covered. The polishing plant according to claim 11, further comprising a control unit which is coupled to the inductive sensor to a signal in response to the presence of a conductive material that over the Polishing pad is available to receive. A polishing plant according to claim 13, further comprising an optical Measuring system includes the optical with the window for optical probing a surface area a substrate disposed on the polishing pad coupled is. The polishing plant of claim 11, wherein the polishing pad has a magnetic material at a portion of the Sensor surface is supported. The polishing plant according to claim 11, further comprising a height adjustment unit which is coupled to the sensor surface and is formed, a height position to change the feeler surface. Polishing pad for a polishing plant with: a base material that is formed is to be mounted on a polishing plate, wherein the base material laterally limited Having areas in which contain a magnetic material is; and a surface for polishing a substrate. The polishing pad according to claim 18, wherein the magnetic Has material ferrite.