System for machining a structural body

Abstract

The invention relates to a system (1) for machining a structural body (2), comprising a carrier unit (3) with a bearing body (9), with a contact side (27) on which the structural body (2) can be mounted for machining, wherein a temperature control section (12) is formed on or in the bearing body (9), a polishing unit (16) on whose upper surface (19) facing the carrier unit (3) a polishing pad (20) is attached or can be attached, wherein in a machining position the carrier unit (3) and the polishing unit (16) are arranged relative to each other in such a manner,that the structural body (2) is in contact with the contact side (27) at a structural body rear side (26) and with the polishing pad (20) at a structural body machining side (28) opposite the structural body rear side (26), and a temperature control unit (13) for varying the temperature of the temperature control section (12) to influence the surface temperature of the bearing body (9) for temperature control of the structural body (2). The invention also relates to a method for machining a structural body (2).

Description

[0001] The invention relates to a system for processing a structural body, in particular for mechanical-chemical polishing of the structural body.

[0002] Such systems are preferably used in the processing of structural components, where fine structures are applied to a processing surface during the manufacturing process. These components can be, for example, wafers onto whose surface conductor structures are applied using standard methods. This requires particularly high flatness and surface quality, in the form of a predefined surface roughness, which is typically achieved by mechanical-chemical polishing. In the mechanical-chemical polishing process, the component is treated using a chemically active polishing dispersion, especially a polishing suspension, resulting in material removal due to mechanical stress and a chemical reaction between the surface of the component and the polishing dispersion.In particular, chemical erosion is a function of the polishing temperature. A higher temperature, which depends on the chosen polishing dispersion and can also be referred to as the processing start temperature, is associated with maximum chemical erosion. The chemical reaction ceases when the processing end temperature, which also depends on the polishing dispersion used, is reached. Chemical erosion can be based directly on the chemical reaction of the polishing dispersion with the substrate or indirectly via a conversion reaction between the polishing dispersion and the substrate. In this latter reaction, for example, the substrate material reacts with the polishing dispersion to form an intermediate product, such as an oxide, which can be more efficiently removed mechanically by relative movement between the substrate and a polishing pad.Accordingly, the required temperature, for example the processing start temperature, should be present at a contact surface between the structural body and the polishing dispersion.

[0003] For optimal machining results, where, for example, the surface roughness and / or flatness of the structural component has reached a specified value, it is necessary that the machining process can be stopped in a defined manner. This requires that the temperature at the contact surface between the structural component and the polishing dispersion is below the final machining temperature shortly before or at the latest upon completion of the machining process, in order to prevent any subsequent reaction, i.e., a reaction after machining has finished, between the material of the structural component and the polishing dispersion.

[0004] The object of the present invention is to improve the machining result.

[0005] The task defined above is solved by a system for processing a structural body, comprising: - A support unit rotatably mounted about a first axis of rotation, comprising a bearing body which is mounted with a first side on a support base and has a contact side opposite the first side on which the structural body can be mounted for machining, wherein a temperature control section is formed on or in the bearing body, - a polishing unit rotatably mounted about a second axis of rotation, on the upper surface of which facing the carrier unit a polishing pad is attached or can be attached, wherein in a machining position the carrier unit and the polishing unit are arranged to each other in such a way that the structural body is in contact with the contact side with a structural body rear side and with the polishing pad with a structural body machining side opposite the structural body rear side, - and a temperature control unit for varying the temperature of the temperature control section to influence the surface temperature of the bearing body for temperature control of the structural body.

[0006] The carrier unit serves to transport the structural body from a storage position to the processing position and to fix the structural body during processing. The structural body can be supported on the contact side of the carrier body in various ways, for example by adhesion or by mechanical fixation, for which, for example, a retaining ring can be attached to the carrier base, connecting the structural body to the carrier base in a form-fit and / or force-fit manner. In the processing position, the structural body is positioned entirely above the polishing pad, and the processing side of the structural body is in contact with the polishing pad. A film of polishing dispersion, which was and / or is applied to the polishing pad before and / or during processing, forms between the polishing pad and the processing side of the structural body.For this purpose, the system according to the invention can include a polishing dispersion dispensing unit designed for the continuous or intermittent application of polishing dispersion to the polishing pad. Preferably, the polishing dispersion is applied centrally to the polishing pad and, as a result of a rotational movement of the polishing unit, distributed radially outwards from the dispensing position across the polishing pad. The polishing unit can be temperature-controlled, in particular heated, to warm the polishing dispersion. However, since a highly porous material is regularly used for the polishing pad, heat conduction from the polishing unit to the film of polishing dispersion formed between the polishing pad and the surface of the structural component being processed is inefficient, meaning that its temperature can only be set and / or varied with insufficient accuracy and / or speed.

[0007] According to the invention, it has been found that the heat conduction to the film of polishing dispersion formed between the polishing pad and the processing side of the structural body, and thus its temperature control, can be improved if the structural body itself, or more precisely, the processing side of the structural body, can be brought to the desired temperature. For this purpose, the temperature of the bearing body, more precisely a surface temperature of the bearing body, is varied by means of the temperature control unit. The temperature control unit can, for example, be designed as an electrical conductor whose heating wires extend at least partially through and / or are arranged within the temperature control section, and which can heat the temperature control section and thus the bearing body.It is also conceivable that the temperature control unit is designed to pump a temperature control fluid and has a pumping device, for example a pump or a compressor, as well as a reservoir for storing the temperature control fluid, wherein fluid lines through which the temperature control fluid can be conveyed extend at least partially through the temperature control section and / or are arranged in it, and can thus cool and / or heat the bearing body.

[0008] Since the structural body is mounted directly on the contact side of the support body, the support body regulates the temperature of the structural body. Due to heat conduction within the structural body, which is a solid with a substantially homogeneous thermal conductivity, the temperature on the working side of the structural body, and thus the temperature of the polishing dispersion film, can be varied. Because of the direct contact between the structural body and the support body, the surface temperature of the support body, or more precisely, the surface temperature of the contact side of the support body, is present on the back side of the structural body. There is an essentially direct proportional relationship between the temperature on the working side of the structural body, which corresponds essentially to the temperature of the polishing dispersion film, and the temperature on the back side of the structural body.This relationship can be used for temperature control by using the surface temperature of the bearing body as the control variable. This also allows the temperature of the structural body to be varied as quickly as possible, whereby a temporal variation of the temperature can also be referred to as the temperature change rate.

[0009] In the context of this application, temperature control is understood to mean varying the temperature, which includes both increasing the temperature by heating and decreasing the temperature by cooling.

[0010] Preferred embodiments of the system are the subject of the dependent claims.

[0011] Advantageously, the temperature control section is arranged in the area of ​​the contact side, particularly adjacent to the contact side. This allows, for example, the contact side to be brought to the temperature of the temperature control section as quickly as possible, without any time delay due to heat conduction within the structural body.

[0012] Preferably, the temperature control section is designed as a cavity for receiving a temperature control fluid, wherein the temperature control unit supplies and / or removes a mass flow of temperature control fluid to and / or from the temperature control section to vary its temperature, and wherein the temperature control section is fluidically connected to the temperature control unit via at least one temperature control line. The fluid line provided for supplying and / or removing the mass flow of temperature control fluid can be designed as a simple fluid line, such that the temperature control unit supplies and removes the temperature control fluid via the line. Alternatively, the fluid line can be designed as a temperature control inlet line, wherein the temperature control fluid leaves the temperature control section through an opening open to the surroundings of the bearing body.

[0013] Preferably, the temperature control section is fluidically connected to the temperature control unit via a temperature control inlet line and a temperature control outlet line. The temperature control unit is configured to provide a continuous mass flow of temperature control fluid, so that the surface temperature of the bearing body can be kept as constant as possible or substantially constant during a selected period of machining. Furthermore, the heat transfer can be specifically influenced by controlling the temperature difference between the temperature control fluid and the temperature control section, and thus the bearing body. Preferably, the mass flow of temperature control fluid supplied and discharged can be controlled separately, if required.

[0014] Preferably, the temperature control inlet line and the temperature control outlet line extend at least partially through the bearing body. Accordingly, the temperature control inlet line and the temperature control outlet line can, for example, be formed within the support base and project from it towards the bearing body, thus enabling a compact system design.

[0015] Preferably, water, steam, nitrogen, helium, compressed air, and / or argon are used as the temperature control fluid. The choice of temperature control fluid can depend on the specific design of the system. For example, water is generally well-suited due to its high heat capacity. Gases such as nitrogen, helium, compressed air, or argon are particularly suitable if the temperature control fluid leaves the temperature control section through the opening or if the risk of potential liquid leakage into the system must be absolutely avoided.

[0016] Advantageously, flow elements are incorporated within the temperature control section to influence heat transfer between the mass flow of temperature control fluid supplied to the section and the bearing element. This improves heat transfer between the temperature control fluid and the bearing element. The flow elements can be designed to increase the surface area in contact with the temperature control fluid and / or to generate turbulence and / or flow structures to enhance convective heat transfer between the temperature control fluid and the bearing element.

[0017] Advantageously, the system further comprises a conditioning unit for conditioning the polishing pad, with a rotatably mounted conditioning head and a third drive unit for driving the conditioning head in a conditioning rotation. Conditioning can take place during the processing of the structural body and / or during a conditioning phase. Conditioning is defined as processing the polishing pad by which it is, for example, smoothed again by the conditioning head, rinsed with demineralized water to remove polishing dispersion residues, and / or a certain amount of material is removed from the polishing pad when it is saturated with polishing dispersion or residues from material removed from the structural body. This extends the service life of the polishing pad before it needs to be replaced.For this purpose, the conditioning system may include a water dispensing unit.

[0018] Preferably, the system further comprises a first drive unit for driving the carrier unit to a carrier unit rotational movement and a second drive unit for driving the polishing unit to a polishing unit rotational movement, wherein the direction of rotation of the carrier unit rotational movement is opposite to or the same as that of the polishing unit rotational movement. It may be provided that the system selects the direction of the carrier unit rotational movement and / or the direction of the polishing unit rotational movement depending on the structure applied to the machining side of the structural body and / or depending on the material removal to be achieved.

[0019] Preferably, the support unit is mounted so as to be radially movable with respect to the second axis of rotation of the polishing unit and has a drive mechanism designed for radial movement. The drive mechanism can, for example, be a linear drive with which the support unit is coupled to its movement. Alternatively, the support unit can also be attached to a cantilever mounted so as to be pivotable about a pivot axis, the pivoting movement of which results in radial movement of the support unit, whereby the drive mechanism can also be designed as a rotary drive.

[0020] Preferably, the bearing element consists of an elastomer. By means of the rubber-elastic properties of an elastomer, in particular silicone, polyurethane, or styrene-butadiene rubber, the bearing element can be used to compensate for an uneven force distribution across the surface of the structural body's machining side, since the machining result is significantly influenced by a uniform force distribution across the entire surface of the structural body's machining side, to which the mechanical material removal is proportional. Furthermore, the rubber-elastic properties can at least partially compensate for a non-planar parallel alignment of the support base and the polishing unit.

[0021] Advantageously, the system further comprises a pressure regulator device which is fluidically connected via at least one fluid line to a compensation chamber formed in the bearing body and which supplies and / or discharges a mass flow of pressure fluid to and / or from the compensation chamber to regulate the pressure in the chamber. The pressure regulator device further advantageously includes at least one proportional valve, in particular a piezo proportional valve, which enables a level of control required to improve the machining result. In particular, the piezo proportional valve can include a piezo actuator designed as a piezo bender, which is exemplified as a strip-shaped element and can have a rubber-elastic sealing element.The piezo bender can be arranged in a housing in which an opening for the passage of pressure fluid can be formed, wherein the opening can be closed by the rubber-elastic sealing element in a closed position of the piezo proportional valve.

[0022] Preferably, the temperature control unit is configured for a temperature change rate of the bearing element greater than 3 K / s, and particularly preferably for a temperature change rate in the range of 4 K / s to 8 K / s. For this purpose, the heating and / or cooling capacity of the temperature control unit is adapted to the mass flow rate of the temperature control fluid. For example, at a high mass flow rate, the capacity of the temperature control unit is increased to ensure sufficient heating or cooling. Temperature sensors, in particular thermocouples or resistance thermometers, can be arranged in the temperature control section to regulate the temperature. These sensors detect the temperature within the temperature control section and transmit a corresponding signal to the temperature control unit via a signal connection, which then adjusts the heating and / or cooling capacity accordingly.Temperature sensors can also be provided to detect the temperature of the structural body, for example non-contact temperature sensors in the form of radiation thermometers.

[0023] The previously defined problem is also solved by a method for machining a structural body. The method is carried out with a system for machining a structural body, in particular with a system according to the invention, comprising: - A support unit rotatably mounted about a first axis of rotation, comprising a bearing body which is mounted with a first side on a support base and has a contact side opposite the first side on which the structural body can be mounted for machining, wherein a temperature control section is formed on or in the bearing body, - a polishing unit rotatably mounted about a second axis of rotation, on the upper surface of which facing the carrier unit a polishing pad is attached or can be attached, wherein in a machining position the carrier unit and the polishing unit are arranged to each other in such a way that the structural body is in contact with the contact side with a structural body rear side and with the polishing pad with a structural body machining side opposite the structural body rear side, - and a temperature control unit for varying the temperature of the temperature control section.

[0024] The process includes the following steps: - Positioning the structural body to be machined on the contact side of the support body - Applying a polishing dispersion to the polishing pad, - Tempering the bearing body to a machining start temperature - Machining the structural body in a machining position, wherein a structural body machining side is in contact with the polishing pad of the polishing unit and the structural body performs a relative movement with respect to the polishing pad.

[0025] The invention will now be explained in more detail with reference to the accompanying drawing and shown therein Fig. 1 a strictly schematic representation of a system for machining a structural body in a machining position, Fig. 2 a strictly schematic representation of a subsystem of the system Fig. 1 consisting of a support base, retaining ring, bearing body and a structural body in an exploded view, and Fig. 3 a strictly schematic representation of a further embodiment of a system for machining a structural body in a machining position.

[0026] In the Fig. Figure 1 shows a system 1 for machining a structural body 2 in a machining position. The system 1 comprises a carrier unit 3 with a carrier base 5 rotatably mounted about a first axis of rotation 4. The carrier base 5 is arranged at a first end of a shaft 6, which extends section by section through a carrier unit housing 7. A second end of the shaft 6, opposite the first end, is connected to a first drive unit 8, which can set the carrier unit 3 into a carrier unit rotational movement. The first drive unit 8 is shown, by way of example, mounted at an end of the carrier unit housing 7 opposite the carrier base 5. Furthermore, the carrier unit 3 comprises a bearing body 9 on which the structural body 2 can be mounted for machining, wherein, by way of example, the carrier unit 3 has a retaining ring 10 that holds the structural body 2 in its position when it is mounted on the bearing body 9.The bearing body 9 is supported at a first side 11 on the support base 5.

[0027] The bearing body 9 has a temperature control section 12 designed as a cavity.

[0028] To supply and / or discharge a mass flow of temperature control fluid to the temperature control section 12, the system 1 comprises a temperature control unit 13, which is fluidically connected to the temperature control section 12 via a temperature control inlet line 14 and a temperature control outlet line 15 for supplying and / or discharging temperature control fluid. The temperature control inlet line 14 and the temperature control outlet line 15 can each also be referred to as a temperature control line.

[0029] Furthermore, system 1 comprises a polishing unit 16, which is rotatably mounted about a second axis of rotation 17 and can be set into a polishing unit rotational movement by a second drive unit 18. A polishing pad 20 is attached, by way of example, to the upper surface 19 of the polishing unit 16 facing the support unit 3.

[0030] For conditioning the polishing pad 20, the system 1 comprises a conditioning unit 21 with a conditioning head 23 rotatable about a third axis of rotation 22 and a third drive unit 24.

[0031] In order to be able to move the carrier unit 3 radially with respect to the second axis of rotation 17, the system 1 also has a traversing drive 25.

[0032] In the Fig. 2 is a subsystem of the system 1 according to the invention for machining the structural body 2, consisting of the support base 5, the retaining ring 10 and the bearing body 9.

[0033] For machining the structural body 2, it is supported with a structural body rear side 26 on the contact side 27, which is opposite the first side 11 of the support body 9, and fixed by the retaining ring 10 at least during machining, wherein a structural body machining side 28, which is opposite the structural body rear side 26, is turned away from the support base 5 and projects towards it.

[0034] After the structural body 2 has been mounted on the contact side 27 of the support body 9, the carrier unit 3 is moved radially into a machining position so that the structural body 2 is completely positioned above the polishing pad 20 of the polishing unit 16 and is in contact with the polishing pad 20 at the machining side 28 of the structural body. To improve the machining of the machining side 28 of the structural body, a chemically active polishing dispersion can be applied to the polishing pad 20. For this purpose, the system 1 can include a polishing dispersion dispensing unit (not shown) configured for continuous or intermittent dispensing of polishing dispersion. Subsequently, the support body 9 is heated so that, via heat conduction within the structural body 2, a machining start temperature is present at the machining side 28 of the structural body that is in contact with the polishing pad 20.For this purpose, a defined mass flow of temperature control fluid is supplied from the temperature control unit 13 to the temperature control section 12 of the bearing body 9, whereby the temperature control fluid is heated to the appropriate temperature by the temperature control unit 13 before entering the temperature control section 12. In this example, this is achieved using a continuous mass flow of temperature control fluid. Alternatively, however, a defined quantity of temperature control fluid can also be supplied to the temperature control section 12 at the beginning, the temperature of which decreases during the processing of the structural body 2 depending on the heat capacity of the temperature control fluid. Here, the mass supplied, the temperature of the supplied mass, and / or the heat capacity (via the selection of the temperature control fluid) can be selected accordingly.For machining, the carrier base 5 is set into a carrier unit rotational movement by the first drive unit 8, and the polishing unit 16 is set into a polishing unit rotational movement by the second drive unit 18, so that material is removed from the structural body machining side 28 by means of the relative movement present between the structural body machining side 28 and the polishing pad 20. To stop the material removal from the structural body machining side 28, cooled temperature control fluid is supplied to the temperature control section 12 by the temperature control unit 13 to reach a final machining temperature.

[0035] In the Fig.Figure 3 shows a further embodiment of system 1 for machining a structural body 2 in strict schematic form. In addition to the elements already described, this includes a pressure regulator device 29. The pressure regulator device 29 is fluidically connected via a fluid line 30 to a compensation chamber 31, which is exemplified by a plurality of compensation chamber chambers 32. The pressure regulator device 29 supplies or discharges a mass flow of pressurized fluid to the compensation chamber 31, i.e., the plurality of compensation chamber chambers 32.

[0036] By way of example, the bearing body 9 is made of an elastomer and is rubber-elastic, so that the pressure within the compensation chamber 31 and / or the plurality of compensation chambers 32 can be regulated by means of the mass flow of pressure fluid supplied to and / or discharged from the compensation chamber 31 and / or the plurality of compensation chambers 32 by the pressure regulator device 29. Thus, the force applied by the support unit 3 to the structural body 2 in the machining position can be varied by means of the pressure prevailing in the compensation chamber 31 and / or in the plurality of compensation chambers 32. In particular, if, as shown by way of example, the compensation chamber 31 is formed from the plurality of compensation chambers 32, a force can be applied uniformly over the entire surface of the machining side 28 of the structural body in order to achieve material removal that is as uniform as possible over the entire surface of the machining side 28 of the structural body.This is particularly advantageous if the support base 5 and polishing unit 16 and / or the polishing pad 20 are not aligned parallel to each other.

Claims

[1] System (1) for processing a structural body (2), comprising: - A support unit (3) rotatably mounted about a first axis of rotation (4) with a bearing body (9) which is mounted with a first side (11) on a support base (5) and has a contact side (27) opposite the first side (11) on which the structural body (2) can be mounted for machining, wherein a temperature control section (12) is formed on or in the bearing body (9), - a polishing unit (16) rotatably mounted about a second axis of rotation (17), on the upper surface (19) of which facing the carrier unit (3) a polishing pad (20) is attached or can be attached, wherein in a machining position the carrier unit (3) and the polishing unit (16) are arranged relative to each other such that the structural body (2) is in contact with the contact side (27) at a structural body rear side (26) and with the polishing pad (20) at a structural body machining side (28) opposite the structural body rear side (26), - and a temperature control unit (13) for varying the temperature of the temperature control section (12) to influence the surface temperature of the bearing body (9) for temperature control of the structural body (2). [2] System according to claim 1, characterized by , that the tempering section (12) is arranged in the area of ​​the contact side (27), in particular adjacent to the contact side (27). [3] System according to claim 1 or 2, characterized by , that the temperature control section (12) is designed as a cavity for receiving a temperature control fluid, wherein the temperature control unit (13) supplies and / or removes a mass flow of temperature control fluid to the temperature control section (12) in order to vary the temperature of the temperature control section (12), wherein the temperature control section (12) is fluidically connected to the temperature control unit (13) via at least one temperature control line (14, 15). [4] System according to claim 3, characterized by , that the temperature control section (12) is fluidically connected to the temperature control unit (13) via a temperature control inlet line (14) and a temperature control outlet line (15), wherein the temperature control unit (13) is prepared to provide a continuous mass flow of temperature control fluid. [5] System according to claim 4, characterized by, that the temperature control inlet line (14) and the temperature control outlet line (15) extend at least partially through the bearing body (9). [6] System according to any one of claims 3 to 4, characterized by that water, steam, nitrogen, helium, compressed air and / or argon is used as the temperature control fluid. [7] System according to any one of claims 3 to 6, characterized by , that within the temperature control section (12) flow elements are arranged to influence heat transfer between the mass flow of temperature control fluid supplied to the temperature control section (12) and the temperature control section (12). [8] System according to one of the preceding claims, further comprising: a conditioning unit (21) for conditioning the polishing pad (20) with a rotatably mounted conditioning head (23) and a third drive unit (24) for driving the conditioning head (23) to a conditioning rotation movement, wherein the conditioning can take place during the processing of the structural body (9) and / or during a conditioning phase. [9] System according to any of the preceding claims, further comprising: - a first drive unit (8) for driving the carrier unit (3) to a carrier unit rotational movement - a second drive unit (18) for driving the polishing unit (16) to a polishing unit rotational movement, wherein the direction of rotation of the carrier unit rotational movement is opposite to or in the same direction as the polishing unit rotational movement. [10] System according to any of the preceding claims, characterized by , that the carrier unit (3) is mounted to be radially movable with respect to the second axis of rotation of the polishing unit (16) and has a traversing drive (25) designed for radial traversing movement. [11] System according to any of the preceding claims, characterized by , that the bearing body (9) is made of a rubber-elastic material, in particular an elastomer. [12] System according to claim 11, further comprising: a pressure regulator device (29) which is fluidically connected via at least one fluid line (30) to a compensation chamber (31) formed in the bearing body (9) and supplies and / or discharges a mass flow of pressure fluid to the compensation chamber (31) for the purpose of regulating the pressure in the compensation chamber (31). [13] System according to claim 12, characterized by that the pressure regulator device (29) has at least one proportional valve, in particular a piezo proportional valve. [14] Method for machining a structural body (2) with a system (1) for machining a structural body (2), in particular with a system (1) according to one of the preceding claims, comprising: - A support unit (3) rotatably mounted about a first axis of rotation (4) with a bearing body (9) which is mounted with a first side (11) on a support base (5) and has a contact side (27) opposite the first side (11) on which the structural body (2) can be mounted for machining, wherein a temperature control section (12) is formed on or in the bearing body (9), - a polishing unit (16) rotatably mounted about a second axis of rotation (17), on the upper surface (19) of which facing the carrier unit (3) a polishing pad (20) is attached or can be attached, wherein in a machining position the carrier unit (3) and the polishing unit (16) are arranged relative to each other such that the structural body (2) is in contact with the contact side (27) at a structural body rear side (26) and with the polishing pad (20) at a structural body machining side (28) opposite the structural body rear side (26), - and a temperature control unit (13) for varying the temperature of the temperature control section (12) to influence the surface temperature of the bearing body (9) to control the temperature of the structural body (2), comprising the steps: - Positioning the structural body to be machined (2) on the contact side (27) of the support body (9) - Applying a polishing dispersion to the polishing pad (20), - Tempering the bearing body (9) to a machining start temperature - Machining the structural body (2) in a machining position, wherein a structural body machining side (28) is in contact with the polishing pad (20) of the polishing unit (16) and the structural body (2) performs a relative movement with respect to the polishing pad (20).

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