CN105518825B - Multizone heater - Google Patents

Abstract

A kind of wafer chuck, including the axle with axis and be connected to axle end plate.The plate can have the part that the axle is extended radially outward beyond from the axis.Temperature sensor can be arranged in the part of plate and electrical lead can extend through axle from the temperature sensor, for temperature of the measurement plate near temperature sensor during manufacture of semiconductor.

Description

multi-zone heater

technical field

This invention relates to heaters used in semiconductor processing, and more particularly to heaters having multiple heating zones and thermocouples for sensing the heating zones.

Background technique

In semiconductor manufacturing, silicon substrates (wafers) are processed at elevated temperatures for the deposition of a variety of different materials. Temperatures typically range from 300°C to 550°C, but can sometimes be as high as 750°C or even higher. The deposited material "grows" in layers on the surface of the silicon wafer. Many of these materials have extremely temperature-sensitive growth rates, so temperature changes on the silicon wafer can affect the local growth rate of the film, resulting in variations in film thickness as the film grows on the silicon wafer.

It is desirable to control the thickness variation of the deposited film. Sometimes it is desirable to have a thicker film in the center of the wafer (like a dome). Sometimes it is desirable for the film to be thicker on the edges (like dimples or dimples). Sometimes it is desirable to keep the film thickness as thin as possible (in the range of tens of angstroms).

One of the most straightforward methods for controlling the temperature of the wafer and thus the thickness distribution of the deposited film is to place the wafer on a heater. The desired film thickness profile can be produced by designing the heater to have a specific power density "map" to produce the desired temperature profile on the silicon wafer. The power density of the underlying heater is increased at one or more locations on the wafer where higher temperatures are desired and decreased at one or more locations where lower wafer temperatures are desired.

Chipmakers want the ability to run different processes in the same chamber. The major equipment used to grow thin films is very expensive (typically over $1 million per process chamber), so it is desirable to maximize the use of the required process chambers and minimize the number of process chambers required. Different temperature treatments using different chemistries are run in the same process chamber to produce different thin films. These different films may also have different growth rate and temperature characteristics. This has led chip manufacturers to desire the ability to rapidly change the power density profile of the heaters in a given process chamber to achieve a desired film thickness profile.

Additionally, it would be desirable for chipmakers to be able to run exactly the same "recipe" in multiple process chambers and produce films with matching film thickness distributions (and other properties that can be affected by temperature such as film stress, refractive index, etc.). Therefore, it would be desirable to be able to produce heaters that can have highly repeatable power density profiles from unit to unit.

Heaters can be manufactured with the ability to vary the power density profile by using multiple independent heater circuits in the heater. By varying the voltage and current applied to different circuits, it is possible to vary the power level at various points within a single circuit. Each part of these specific circuits is called a "zone". By increasing the voltage (and thus the current when the heating elements are resistive heaters) for a given zone, the temperature in that zone can be increased. Conversely, when the voltage is reduced for a region, the temperature in that region is reduced. In this way, different power density maps can be generated by the same heater by varying the power for each zone.

At least two limiting factors can affect a chipmaker's ability to use multi-zone heaters effectively. The first limiting factor is that prior art heaters have only one control thermocouple. Only one control thermocouple can be used because the current plate and shaft design for the heater only allows the location of the thermocouple at the center of the heater plate or within an approximate 1 inch radius of the heater center. Thermocouples are made of metals that are incompatible with, and therefore must be isolated from, the processing environment of the silicon wafer. Additionally, for faster response of the thermocouple (TC), it is preferable to operate it in an atmospheric pressure environment rather than the vacuum environment of a typical process chamber. Therefore, thermocouples can only be located in the central hollow area of the heating shaft which is not connected to the process environment. If there is a heated zone located outside the 2 inch diameter of the heated shaft, no thermocouples can be installed there to monitor and help control the temperature of that heated zone.

This limitation has been addressed by utilizing a "slaved" power ratio to control heating zones located outside of the heater's central region. This power ratio is established from the power applied to the central zone and every other zone to generate the desired power density map. A central control thermocouple monitors the temperature of the central zone, and (based on feedback from the central control thermocouple) power applied to the central zone is then applied to all zones adjusted by a pre-established power ratio. For example, for a dual zone heater, assume that the ratio of power applied to the outer and inner zones is 1.2 to 1.0 to generate the desired temperature profile. Assume that the heater control system determines that a voltage of 100VAC is required to achieve the proper temperature by reading the temperature data provided by the central control thermocouple. A controlled proportional control method was utilized whereby a voltage of 120 AVC was applied to the outer heating zone and a voltage of 100 VAC was applied to the inner heating zone. The power density map can thus be adjusted by changing the controlled ratio.

This leads to a discussion of the second limiting factor. Prior art heaters have resistance variations inherent in embedded heaters. Due to the high temperature and high pressure required in the manufacturing process of current ceramic heaters, the achievable resistance tolerance can be close to 50%. In other words, the typical resistance for a semiconductor grade ceramic heating element is in the range of 1.8 ohms to 3.0 ohms (at room temperature the heating element material is usually molybdenum which increases in resistance as the operating temperature increases).

This variation poses the problem of maintaining a repeatable power density profile between units for multi-zone heaters controlled by controlled ratio methods. For single zone heaters, resistance variation is not a problem since the control thermocouple is used to monitor the actual operating temperature and adjust the power level supplied to the heater accordingly. But if it is a multi-zone heater, and the resistance variation of the heating elements can approach 50%, then the controlled ratio control method will not be able to generate repeatable power density patterns from unit to unit.

The requirement was to create a heater design that would allow for the installation of multiple control thermocouples that could be physically located in the respective heating zones to allow feedback and direct control, yet still keep the thermocouples from the process chamber isolated from the processing environment.

Description of drawings

The drawings described herein, which are schematic in many respects, are for illustration only and are not intended to limit the scope of the present disclosure.

FIG. 1 is a view of a plate and spindle apparatus used in semiconductor processing according to some embodiments of the present invention.

2 is a cross-sectional view of a connection between a plate and a shaft according to some embodiments of the invention.

Figure 3 is a view of a plate and shaft arrangement in a processing chamber according to some embodiments of the present invention.

Figure 4 is a view of a heater arrangement according to some embodiments of the present invention.

5 is a schematic cross-sectional view of a multi-zone heater according to some embodiments of the present invention.

Figure 6 is a schematic bottom view of a multi-zone heater according to some embodiments of the present invention.

Figure 7 is a schematic illustration of a connected cover plate according to an embodiment of the present invention.

Figure 8 is a schematic illustration of a cover plate according to some embodiments of the present invention.

9 is a perspective view of a heater according to some embodiments of the present invention.

Figure 10 is a perspective exploded view of a heater according to some embodiments of the present invention.

11 is a schematic cross-sectional view of a heater with a multi-layer plate according to some embodiments of the present invention.

12 is an enlarged partial cross-sectional view of a multilayer board according to some embodiments of the present invention.

13 is a schematic cross-sectional view of a heater with multiple heating zones and thermocouples according to some embodiments of the present invention.

14 is an enlarged cross-sectional view of the connection region of the plate and shaft taken along line 14-14 in FIG. 13 according to some embodiments of the present invention.

15 is a top view of the central bushing taken along line 15-15 in FIG. 14, according to some embodiments of the present invention.

16 is a partial cross-sectional view illustrating aspects of the central bushing taken along line 16-16 in FIG. 15, according to some embodiments of the present invention.

17 is a map of multiple heating zones taken along line 17-17 in FIG. 13, according to some embodiments of the present invention.

Detailed ways

In one embodiment of the present invention, a multi-zone heater is provided having multiple thermocouples to enable independent monitoring of the temperature of different heating zones. Individual thermocouples may have their leads branch off from the shaft of the heater in a channel or recess that can be closed with a connection process that results in a shaft suitable to withstand the process chemistry in the process chamber. The airtight seal of the internal atmosphere of the product. Individual thermocouples may have their leads diverged from the shaft of the heater in the spaces, recesses or cavities between the layers, and the layers may be connected using a connection process that results in a material suitable to withstand the process chamber Hermetic seal of the shaft and the internal atmosphere of the handling chemicals. The thermocouple and its leads can be encapsulated by a joining process in which a first plate layer or channel cover, which can act as a base plate layer, is brazed to a second plate layer or channel cover using any suitable joining material such as aluminum. heating plate.

FIG. 1 illustrates an exemplary plate and shaft apparatus 100 such as a heater used in semiconductor processing. In some aspects, plate and shaft assembly 100 is composed of a ceramic, such as aluminum nitride. The heater has a shaft 101 which in turn supports a plate 102 . Plate 102 has a top surface 103 . The shaft 101 may be a hollow cylinder. Plate 102 may be a flat disk. May have other subcomponents. In some processes of the present invention, the plate 102 may be fabricated separately in an initial process involving a processing furnace in which the ceramic plate is formed. In some embodiments, the plate may be attached to the shaft using a cryogenic hermetic attachment process as described below.

Figure 2 shows a cross-sectional view in which a first ceramic part (which may be a ceramic shaft 191) may for example be connected to a second ceramic part which may be made of the same or a different material and which may be is a ceramic plate 192 . A joining material such as a brazing layer 190 may be included, which can be selected from the combinations of brazing layer materials described herein and which may be delivered to the connection according to the methods described herein. In some aspects, the plate can be aluminum nitride and the shaft can be aluminum nitride, zirconia, aluminum or other ceramics. In certain aspects, it may be desirable to use a shaft material with a low conductive heat transfer coefficient.

With respect to the connection shown in Fig. 2, the shaft 191 may be positioned such that it abuts the plate with only the brazing layer interposed between the surfaces being connected eg surface 193 of the shaft and surface 194 of the plate. The contact surface 194 of the plate 192 may be located in a recess 195 in the plate. For clarity of illustration, the thickness of the connecting portion is exaggerated. In an exemplary embodiment, both the plate and the shaft may be made of aluminum nitride and both have been previously formed separately using a liquid phase sintering process. The plates may be approximately 9-13 inches in diameter and 0.5-0.75 inches thick. The shaft may be a hollow cylinder with a length of 5-10 inches and a wall thickness of 0.1 inches and an outer diameter in the range of 1-3 inches. The plate may have a recess adapted to receive the outer surface of the first end of the shaft.

As shown in Figure 3, the brazing material of the joint used on the heater or other device can be bridged between two different atmospheres, both of which can present significant problems for existing brazing materials . On the outer surface 207 of the heater 205 of semiconductor processing equipment, such as a semiconductor wafer holder, the brazing material must be compatible with the ongoing processing and the environment 201 present in the semiconductor processing chamber 200 in which the heater 205 is used. The environment 201 present in the processing chamber 200 may include fluorochemicals. The heater 205 may have a substrate 206 secured to the top surface of a plate 203 supported by a shaft 204 . On the inner surface 208 of the heater 205, the brazing layer material must be compatible with a different atmosphere 202, which may be an oxygen-containing atmosphere. Existing brazing materials for use with ceramics do not yet meet these two criteria. For example, brazing elements comprising copper, silver or gold may interfere with the lattice structure of the silicon wafer being processed and are therefore not suitable. However, in the case of a brazed connection connecting the heating plate to the heating shaft, the interior of the shaft is usually subjected to high temperatures and has an oxygen-containing atmosphere in the center of the hollow shaft. Portions of the soldered connection that will be exposed to this atmosphere will oxidize and can oxidize into the connection, causing a failure of the hermeticity at the connection. In addition to structural attachment, the connection between the shaft and the plate of these devices used in semiconductor manufacturing must be hermetic in many, if not all, applications.

FIG. 4 shows an example of a schematic view of a heater string used in a semiconductor processing chamber. Heater 300 , which may be a ceramic heater, can include radio frequency antenna 310 , heating element 320 , shaft 330 , plate 340 and mounting flange 350 .

In some embodiments of the present invention, as shown in FIG. 5 , a device for application in semiconductor manufacturing process, such as a wafer clamp or heater 500 , can be provided. The apparatus can include an elongated shaft 516 which can be cylindrical and provided with opposing first and second ends 517, 518 and a central longitudinal axis extending between the ends 517, 518. 519. A passageway or central bore 504 extends through the shaft 516 from a first end 517 to a second end 518 . Plate 521 is connectable to first end 517 of shaft 516 . Plate 521 can have any suitable shape such as cylindrical and can be centered on axis 519 . In one embodiment, the radius of the plate 521 is greater than the radius of the shaft 516 . In one embodiment, the plate 521 has a portion 522 , such as an annular portion, that extends radially outward from the axis 519 beyond the shaft 516 . Each of the shaft 516 and the plate 521 can be made of any suitable material, such as a ceramic material, and in one embodiment both the shaft and the plate are made of aluminum nitride. The plate 521 can be provided with a plurality of heating zones each having at least one heater therein. In one embodiment, the plate 521 has a first or central heating zone 526 which can be centered, for example, on the axis 519 ; a second or central heating zone 527 and a third or edge heating zone 528 . Each of the heating zones may have any suitable shape when viewed in plan, and in one embodiment, central zone 526 is circular in plan and central zone 527 and edge zone 528 are circular in plan. . The heating zones can overlap (eg, as shown in Figure 5), or be non-overlapping and radially spaced from each other.

The device 500 can be provided with a plurality of temperature sensors, eg at least one temperature sensor per heating zone. In one embodiment, the first temperature sensor 505 is disposed near or adjacent to the central heating zone 526 in the plate 521 and the second temperature sensor 506 is disposed near or adjacent to the central heating zone 527 in the plate , the third temperature sensor 507 is arranged near or adjacent to the edge heating zone 526 in the plate. In one embodiment, each of the temperature sensors is arranged at the radial center of the respective heating zone, although other positioning of the temperature sensors relative to the respective heating zone is also within the scope of the invention. In one embodiment, each of the second and third temperature sensors 506 , 507 is arranged in a portion 522 of the plate 521 . In one embodiment, the temperature sensors 505, 506, 507 are radially spaced apart from each other, and in one embodiment, the second temperature sensor 506 is spaced radially outward from the first temperature sensor 505, while the third temperature sensor 507 Spaced radially outwardly from the second temperature sensor 506 . Each of the temperature sensors may be of any suitable type, and in one embodiment each of the temperature sensors is a thermocouple.

Electrical leads extend from each of the temperature sensors to a first end 517 of the shaft 516 and through the central bore 504 to a second end 518 of the shaft. In this regard, one end of the first electrical lead 531 is electrically coupled or electrically connected to the first sensor 505, one end of the second electrical lead 532 is electrically coupled or electrically connected to the second sensor 506, and the third electrical lead 533 One end of is electrically coupled or connected to the third sensor 507 . Each of the lead wires extends through the shaft 516 so as to be attachable at the second end 518 of the shaft and allow independent monitoring of the temperature of the plate 521, more specifically the temperature of the plate in the vicinity of the respective temperature sensor and thereby The temperature in the vicinity of the respective heating zones 526, 527, 528 is monitored.

Plate 516 can be formed in any suitable manner, and in one embodiment, the plate is made of multiple layers, such as multiple planar layers. In one embodiment, a first ply or cover 501 of device 500 may be bonded to the backside of a second ply or heating plate 502 of device 500 so as to cover a hollow area or recess 503 which It may be connected or communicated with the heating shaft hollow core 504 . The recesses can act as conduits for the temperature sensor leads 531-533, and one or more of the leads 531-533 can be disposed in each recess or channel. The use of radial power distribution feeders, recesses or channels such as covered hollow areas allows for individual control of thermocouples for direct monitoring of the local temperature at each heating zone in multi-zone heater 500, such as heating zones 526-528. Thermocouples 505, 506, 507 may be mounted within respective thermowells 508, 509, 510 located in each individual heating zone. Thermocouples can be fitted into these sleeves, which are located in the covered hollow area or channel 503 . In some embodiments, machining of the plate may be performed in channel 503 to allow for deeper mounting of temperature sensors or thermocouples 505-507. The thermocouples can then be covered with a ceramic cover plate 501 positioned on the backside of the heating plate and between the heating plate and the shaft. The heating plate 502, the hollow area cover plate 501 and the heating shaft 516 can then be joined together. This isolates the thermocouples from the process environment and provides direct feedback of the temperature of each heating zone for routine control. In some heater designs, the heater is fully embedded in the board during processing of the board. Such processing may require high temperatures, which may be in the range of 1700°C, and high stamping contact forces during formation of the plate. While the heating element itself may be adapted to withstand such treatment, the thermocouples 505-507 and the leads 531-533 for the thermocouples, which may be made of Inconel, cannot withstand this treatment. become. Where thermocouples 531 - 533 are installed after final sintering and stamping of ceramic plate 521 , the thermocouples must be protected accordingly from processing chemicals that will be exposed to heater 500 during its use. The temperature of areas of the plate 521 with individual heaters is monitored using multiple thermocouples to allow the temperature of these areas of the plate to be controlled based on actual temperature readings.

Thermowells may extend into plate 521 to the level of the heating elements. In some embodiments, the heating element may have an open area so that the thermowell does not protrude down into the heating element but to the same depth in an area where there is a gap or space in the heating element . In certain embodiments, the hollow region 503 and thermowells may be machined into the heating plate after the heating plate is machined to have the multi-zone heating element therein. When manufacturing the heating plate, the multi-zone heating element can be in the ceramic heating plate. Hollow region cover plate 502 may be attached to heated plate 501 and, in some aspects, to a portion or end 517 of shaft 516 using a cryogenic attachment process as described herein.

6 is a bottom view of a plate, such as plate 521 , in semiconductor processing wafer chuck 500 with a shaft, such as shaft 516 , attached thereto. A recess, slot or hollow channel region 503 extends radially outward from a portion of the plate centrally located on the hollow shaft 516 . One or more thermowells can be located within this hollow channel region 503 to allow the insertion of temperature sensors or thermocouples into the respective heating zones (such as the central heating zone 527 and edge heating zone 528 which would otherwise not be directly monitored) corresponding heating elements in the

7 illustrates a cross-sectional view of a portion of a heating plate 502 having a recess, space or hollow region 503 and a cover plate 501 according to some embodiments of the invention, the heating plate 502 being included as, for example, for use in semiconductor processing part of the heater or wafer holder. The cover plate 501 may be adapted to fit in a slot, recess or opening provided in the bottom of the heating plate. Slots, channels, recesses or slits are provided in at least one of the heating plate 502 and the cover plate 503 . In one embodiment, a recess or channel 503 shown in the cross-sectional view of FIG. 7 may be located below the slit and adapted to tap electrical leads or couplings 520 from the temperature sensor or thermocouple to the center of the shaft. In particular, suitable temperature sensors or thermocouples are arranged in the plate radially beyond the outer diameter of the shaft and thus do not overlap the shaft. Because the channel 503 may experience the atmosphere in the center of the shaft, which is likely to be oxidized, the connection 521 can be, for example, any of the connection layers disclosed herein that attach the cover plate 501 to the heating plate 502 to bridge different atmosphere. Such an atmosphere within the channel may allow significantly better thermocouple function for the thermocouples in the region of the channel. The other side of the connection will experience the atmosphere within the process chamber, which may include corrosive process gases such as fluorine-containing chemicals. Appropriate joining methods result in joints compatible with these different atmospheres, such as hermetic joints of the type disclosed herein. The electrical leads 520 of the device or heater illustrated in FIG. 7 extend through the heating plate 502 in a recess, channel or passage that is hermetically sealed from the environment of the semiconductor processing chamber in which the device is used. Hermetically isolated.

8 illustrates a cross-sectional view of a portion of a first plate layer or heater plate 502 included as part of a heater or wafer holder, for example for use in semiconductor processing, wherein A second ply or hollow cover 530 is adapted to be attached to the bottom of the heating plate 502 . The heating plate 502 and the cover plate 530 can form a plate of a heater such as the plate 521 . A hollow cover plate 530 may cover the electrical leads or thermocouple coupling wires 520 and the thermocouple wells in the bottom of the heating plate. At least one of the opposing surfaces of the heating plate 502 and the cover plate 530 is provided with a groove, channel, recess or slit for making the formed recess, channel, recess or slit 545 hermetic to the environment of the semiconductor processing chamber Hermetically isolated from ground and suitable for use as a conduit for electrical leads or wires 520 coupled to a temperature sensor or thermocouple disposed in a portion of the heating plate extending radially outward from the axis of the heater . A suitable tie layer or connection 546 , which can be, for example, any of the tie layers disclosed herein, can attach the cover plate 530 to the heating plate 502 and form a hermetic seal therebetween. In the embodiment illustrated in FIG. 8 , channel 545 is located in or extends through cover plate 530 , rather than within or extending through heating plate or structure 502 .

9 and 10 illustrate a heater 550 according to some embodiments of the present invention in perspective view and partially exploded perspective view, respectively. The heater 550 is similar to the heater described above and the same reference numerals are used to describe the same components in the heater 550 . A hollow cover plate 551 is provided and the hollow cover plate 551 may have a continuous ring structure or ring member 552 adapted to be mounted on the shaft 516 and the bottom of the heating plate 502 between. In one embodiment, the cover plate 551 and the ring structure or ring 552 are integrally formed from the same material and thus are not distinct components. At least one of the opposing surfaces of the heating plate 502 and the cover plate 551 is provided with a groove, channel, recess or slit for forming a hermetically sealed isolation from the environment of the semiconductor processing chamber and suitable for coupling to a temperature sensor Or conduits for the electrical leads 532 , 533 of thermocouples arranged in the portion of the plate 521 extending radially outward from the axis 516 of the heater 550 . In the heater 550, as opposed to being in or extending through the heating plate or heating structure 502, slots, channels, recesses or slots for the temperature sensor leads are in or extending through the cover plate 551. Cover plate 551 . The hollow cover plate 551 allows the routing of thermocouple leads or wires 532, 533 from the bottom of the plate 521, outside the perimeter of the shaft 526, to the center of the shaft. In some embodiments, heating plate 502, hollow cover plate 551 with ring structure 552, and shaft 516 may be connected simultaneously in one heating operation that brazes these components together. In this regard, any of the connection processes and layers disclosed herein may be used.

In some embodiments of the invention, as can be seen from the expanded view of FIG. 11 , a plate shaft device 556 such as a heater or wafer holder has a plate assembly or plate 557 and a shaft 558 . The plate assembly 557 has layers 561 , 562 , 563 which can be fully sintered ceramic layers before they are assembled into the plate assembly 557 . A first or top layer 561 covers a second or middle layer 562 , wherein the electrode layer 564 is located between the top layer 561 and the middle layer 562 . The middle layer 562 covers the bottom layer 563 , wherein the heating layer 565 is located between the middle layer 562 and the bottom layer 563 .

In some embodiments, thermocouples may be installed between the plies to monitor the temperature at different locations. The multilayer board assembly may allow manipulation of areas on one or more surfaces of one or more of the boards so that matching of the surfaces may be accomplished after final sintering of the ceramic board layers. In addition, this manipulation of the surfaces also allows the assembly of components into the surfaces of the plies and into the spaces between the plies.

The layers 561, 562, 563 of the plate assembly 557 may be made of ceramics such as aluminum nitride in the case of heaters, or other materials including alumina, doped alumina, nitride, etc. in the case of electrostatic chucks. aluminum, doped aluminum nitride, beryllium oxide, doped beryllium oxide, and others). The layers 561 , 562, 563 of the plate assembly making up the substrate support may be fully sintered ceramics before their introduction into the plate assembly 557 . For example, the layers 561, 562, 563 can be fully sintered when the board is in a special furnace with high temperature and high contact pressure or when the board is treated by strip casting or spark plasma sintering or other methods, and then according to their use and their appearance on the board Components are placed in the stack to be machined to final dimensions as required. The plate layers 561, 562, 563 can then be joined together with the connection layer 567 using a brazing process, which allows final assembly of the plate assembly 557 without the need for specialized high temperature furnaces equipped with punches for high contact stress .

In embodiments where the shaft is also part of the final assembly, such as in the case of a plate-shaft arrangement, the joining process step of joining the plate assembly 557 to the shaft 558 can also be performed without the need for specialized high-temperature In the case of a furnace, this is done using a brazing process. In some embodiments, the process of connecting the plies and plate assemblies to the shaft may be done in a simultaneous processing step. Shaft 558 may be connected to plate assembly 557 using connection layer 568 . Bonding layer 568 may be the same brazing element as bonding layer 567 in some embodiments.

Improved methods for manufacturing panels or panel assemblies may involve the time-consuming and expensive steps of joining the panel assembly layers into the final panel assembly without the need for additional processing using high temperatures and high contact pressures, which have been described above and will This method is described in more detail below. Embodiments according to the present invention may utilize a brazing method for joining ceramics to join the plies. An example of a brazing method for joining together first and second ceramic parts may include the steps of: bonding the first and second ceramic parts with a brazing layer (selected from the The group consisting of aluminum and aluminum alloys between the parts) is joined together, the brazing layer is heated to a temperature of at least 800 ° C, and then the brazing layer is cooled to a temperature below its melting point, so that the brazing layer hardens and forms a gas A tight seal for connecting the first member to the second member. Various geometries of brazed joints can be achieved according to the methods described herein.

In some embodiments of the invention it is possible to propose a plate assembly with multiple layers such that there are supports between the plate layers so that when the connecting layers are heated and light pressure is applied axially to the plates there is a slight axial compress in a direction so that the connecting layer is moderately thinned until the support on one board touches the adjacent board. In certain aspects, this allows for control not only of the thickness of the connection, but also of the dimensions and tolerances of the plate assembly. For example, the parallelism of the structure of the various panels can be set by mechanical tolerances with respect to the panel layers, and this aspect can be maintained during the connection process with the supports. In certain embodiments, post-joining dimensional control can be achieved using a circumferential outer ring on one ply that overlies an inner ring on an adjacent ply to provide axial consistency. In some embodiments, one of the outer ring or the inner ring may also contact the adjacent plate in an axial direction perpendicular to the plates, so that position control is also achieved in this axial direction. The axial position control can also thereby determine the final thickness of the connecting layer between two adjacent plates.

In some embodiments of the invention, the material of the electrodes between the layers may be the same as that of the connection layer and can function as both a connection layer and an electrode. For example, the area previously occupied by an electrode in an electrostatic chuck can instead be occupied by a connection layer that has the dual function of being an electrode and a connection layer that, when used as an electrode, is used, for example, to provide an electrostatic clamp. Force, when used as a connecting layer, which connects two plates with the connecting layer in between. In this embodiment, a labyrinth may be located around the periphery of the two connected plates so that line of sight and access to the live electrodes from areas outside the plates is substantially minimized.

Figure 12 illustrates a partial cross-sectional view of a plate assembly according to some embodiments of the invention. The board assembly is a multi-layer board assembly where heaters and electrodes are located between different layers. The layers are connected by soldering elements and the final position of the plate in a direction perpendicular to the plane in which the main plane of the plate lies is determined by the supports 578, 579 on the plate.

A first or top ply 571 overlies a second or lower ply 572 . The lower ply 572 covers the third or bottom ply 573 . Although three plies are illustrated in FIG. 12 , a different number of plies may be used as desired for a particular application. The top ply 571 is connected to the lower ply 572 with a multifunctional connection layer 576 . The multifunctional connection layer 576 is adapted to connect the top plate layer 571 to the lower plate layer 572 and is suitable as an electrode. Such an electrode may be a connecting layer, which is essentially a disc, wherein the connecting material also serves as an electrode. As shown in Figure 12, the support 578 is adapted to control the position of the top ply 571 with respect to the lower ply 572 along a vertical direction perpendicular to the main plane of the ply. The edge of the top deck layer 571 is adapted to block views along a border 577 between the two panels at their perimeters. The thickness of the tie layer 576 may be dimensioned such that the tie layer 576 is in contact with the top ply 571 and the bottom ply 572 prior to the heating and joining steps of the ply assembly.

The lower plate layer 572 covers the bottom plate layer 573 . The heater 574 is located between the lower plate layer 572 and the bottom plate layer 573 . In this regard, a recess, cavity or cavity is provided in at least one of the opposing surfaces of the lower ply 572 and the bottom ply 573 to form a recess, cavity or cavity 580 for receiving the heater 574 . In one embodiment, as shown in FIG. 12 , a recess or cavity 580 is formed in the upper surface of the chassis layer 573 for receiving the heater 574 . The recess 580 can be of any suitable size and shape and can be circular when viewed in plan, for example, so as to form a cylindrical recess. The connection layer 575 connects the lower plate layer 572 to the base plate layer 573 . The tie layer 575 may be an annular ring located within the perimeter of the plies. The support 579 is adapted to control the position of the lower ply 572 relative to the bottom ply 573 along a vertical direction perpendicular to the main plane of the ply. During the joining step of the board assembly, the components as shown in Figure 12 may be pre-assembled and the board pre-assembly subsequently joined using the processes described herein to form a complete board assembly. In certain embodiments, this plate pre-assembly can also be pre-assembled together with the shaft and shaft connection layers, so that a complete plate-shaft arrangement can be joined in a single heat treatment. This single heat treatment may not require a high temperature furnace or a high temperature furnace with punches adapted to provide high contact stress. Additionally, in some embodiments, a complete plate shaft assembly may not require any post-attachment machining steps and still meet the tolerance requirements for such devices in practical use in semiconductor manufacturing.

In certain embodiments, the top and bottom layers are aluminum nitride. In certain embodiments, the tie layer is aluminum. Examples of connection processes and materials are discussed below.

13 is a cross-sectional view of a plate-and-spindle assembly 600, which may be a heater, wafer holder, pedestal, or susceptor, wherein multiple heating zones and multiple thermocouples are used according to certain embodiments of the present invention. Example multilayer board 601. An elongate shaft is provided having a first end 641 and an opposite second end 642 and a longitudinal axis 643 extending between the ends 641 , 642 . The first end 641 of the shaft 602 can be coupled to the bottom center of the plate 601 by any suitable means, including those disclosed herein. In these embodiments, the use of a hermetic bonding layer that is also suitable for withstanding the corrosive treatment chemicals can be used to join adjacent plates together to allow the temperature sensor to be inserted into the portion 605 of the plate 601, said portion 605 The region enclosed by the interior 603 of the shaft 602 extends radially outward and is isolated from corrosive process gases to which the heater may be subjected. Appropriate lift pin holes or openings 630 can be provided in plate 601 , eg, as shown in FIG. 13 .

In some embodiments, the use of multi-layer boards allows access to the spaces between the layers where thermocouples can be placed in areas that would otherwise be impossible to monitor. For example, in a plate shaft arrangement 600 such as that shown in Figure 13, all power and monitoring is typically routed through the hollow center or central passageway 603 of the shaft 602 and exits the process chamber via a chamber feedthrough. In prior art devices, where the entire ceramic plate shaft assembly is heat sintered together, the only area available for embedding thermocouples and routing telemetry down the hollow shaft is in the area in the center of the hollow shaft. For example, a long drill bit adapted to run down the center of the hollow shaft can be used to drill a hole in the bottom of the plate. A thermocouple can then be inserted into the hole and used only to monitor the temperature of the plate in the central region. The limitation of where thermocouples can be mounted precludes monitoring the temperature at locations falling outside the interior of the hollow shaft.

In some embodiments of the invention, a center liner 604 may be used to assist in sealing the inner space between the plies from the atmosphere that may exist in the shaft. In such an embodiment, the central bushing 604 may serve as a feedthrough from the central portion of the shaft 602 to the inner layer space between the plies.

In some embodiments, the plate 601 of the heater 600 may be assembled from three plate layers. Each of the plies may be a fully sintered ceramic such as aluminum nitride. Each of the plies may be previously machined to finished or near-finished dimensions before being assembled into a multi-layer board assembly. A first or top ply 612 may cover a second or middle ply 611 which in turn may cover a third or bottom ply 610 . Each of the plies may be cylindrical, and in one embodiment, each of the plies has the same transverse dimension or diameter that is the same as that of the plate 601 equal. The perimeter of the middle ply may be connected to the bottom ply 610 using a tie layer 614 . The metal layer 613 between the top plate layer 612 and the middle plate layer 611 may serve as an RF layer, and as a connection layer between these plate layers. Plate 601 has a portion 605 extending radially outward from axis 643 beyond shaft 602 .

Between the middle ply 611 and the lower ply 610 there are one or more heating elements. The middle ply 611 may be adapted to receive a heating element such that the heating element 621 is located in a slot 620 in the bottom of the middle ply 611 . An example of a multi-zone heating element layout can be seen in FIG. 17 . For a total of six zones, the heating element is divided into three radial zones, each of which has two half zones. In this regard, the plate 602 includes: a central heating zone 647, which can be annular and divided into first and second central halves 647a, 647b; a central heating zone 648, which can be annular and divided into first and second middle half regions 648a, 648b; and an edge heating region 649, which can be annular and divided into first and second edge half regions 649a, 649b. Each of these half regions can be semi-circular. The central heating zone 647 can be centered on the axis 643, the central heating zone can be spaced radially outward from the axis 643 and the central heating zone 647, and the edge heating zone can be spaced radially outward from the axis and the central heating zone. Two of the radial zones, central heating zone 648 and edge heating zone 649, can be located in portion 695 of plate 601 and completely outside the perimeter of the interior of the hollow shaft. The heating element 621 can be made of molybdenum and can be potted into the slot with AlN potting compound 622 . Feed wires 646 for the heating elements 621 can be deployed from the central bushing to deliver power to the various heater circuits.

In one embodiment, such as shown in FIG. 17, at least one first temperature sensor 651 is arranged near or adjacent to the central heating zone 647 in the plate 601, and at least one second temperature sensor 652 is arranged in the plate. Near or adjacent to the central heating zone 648, and at least one third temperature sensor 653 is arranged in the panel near or adjacent to the edge heating zone 649. Any suitable way of positioning the temperature sensors relative to the respective heating zones is within the scope of the present invention. In one embodiment, each of the second and third temperature sensors 652 , 653 is arranged in portion 605 of plate 601 . Accordingly, temperature sensors located in the heating zones 648 , 649 adapted to provide temperature monitoring are positioned in the plate at a radial distance greater than the inner radius of the shaft 602 . In one embodiment, the temperature sensors 651, 652, 653 are radially spaced from each other, and in one embodiment each second temperature sensor 652 is spaced radially outward from at least one first temperature sensor 651, each The third temperature sensor 653 is spaced radially outward from the at least one second temperature sensor 652 . Each of the temperature sensors can be of any suitable type, and in one embodiment, each of the temperature sensors is a thermocouple.

Electrical leads 661 extend from each of the temperature sensors 651 to 653 to the first end 641 of the shaft 601 and through the central bore 603 to the second end 642 of the shaft. Each of the lead wires 661 extends through the shaft 601 so as to be able to be connected to the second end 642 of the shaft and to allow independent monitoring of the temperature of the plate 601 and, more specifically, the temperature of the plate in the respective heating zones 647, 648, 649. nearby temperature.

In embodiments such as those shown in Figures 13 to 16, the bottom surface of the middle ply 611 may be fitted with different components. In certain aspects, one or more recesses, channels, grooves or slots 662 may be machined into the surface for mounting heating element 621 and electrical leads 661 . Such one or more recesses can comprise a single cavity, which can, for example, be cylindrical and centered on axis 643 in one embodiment. Holes can be drilled into this surface to serve as thermowells for mounting thermocouples 651-653. After this machining, the heating element 621 can be installed and packaged. In certain embodiments, the heating element may be a molybdenum wire placed in operation. In some embodiments, the heating elements may be deposited into the slots using thick film deposition techniques. Thermocouples 651 to 653 may also be mounted and packaged. The heating element may be attached to a feed line 646, which may be a bus. In embodiments using a central bushing, feed wires 646 and thermocouple leads 661 may be routed through the central bushing. The stack of multilayer plates 601 can be assembled, for example, in an upside-down fashion, wherein all elements, including the solder layers, are assembled into a pre-assembly which is then processed into a final complete heater assembly. The soldering steps according to the description herein join all components utilizing a hermetic seal adapted to withstand the atmosphere experienced by the heater while supporting semiconductor fabrication, which may include an oxygen-containing atmosphere and Fluorine chemicals.

Where leads are routed, such as thermocouple leads 661 with an Inconel exterior, through the central bushing 604, these leads may pass through the central bushing and also be sealed against the brazed elements. For example, a lead wire may pass through a countersink hole in the central bushing, and a cylindrical brazing element may be placed around the lead wire prior to the brazing step. The center bushing 60 also allows the inner plate space between the middle plate layer 611 and the bottom plate layer 610 to be hermetically sealed from the inner space of the shaft. As shown in FIG. 14 , a tie layer 615 may be used to isolate the shaft from the bottom of the chassis layer 610 , and another tie layer 616 may be used to isolate the center bushing 604 from the upper surface of the chassis layer 610 . In some embodiments, the inner plate will be sealed under vacuum with a hermetic seal when the entire heater assembly is heated in vacuum during the brazing step to join all the different surfaces to which the various joining layers are to be attached. space. In certain aspects, the thermocouples will be better thermally isolated from the temperature of the area outside the area where the thermocouples are installed by the inner plate layer where the thermocouples are installed.

15 and 16 illustrate the central bushing 604 in top and partial cross-sectional views, respectively. The central bushing may serve as a sealed feedthrough that isolates the central region of the shaft from the inner plate space between the middle ply 611 and the bottom ply 610 . Lead wires 646 supplying power to the heater and thermocouple wires 661 can be routed through the central bushing and sealed with brazing material in the same brazing process step that interconnects and seals the other components.

Figure 17 illustrates a multi-zone heating element, such as heater 600, as seen in certain embodiments of the present invention. For a total of six heating zones 647a, 647b, 648a, 648b, 649a, 649b, the heating elements are divided into three radial zones 647, 648, 649 in the plate 601, as shown in plan view in FIG. Each of the orientation areas 647, 648, 649 has two half areas. Two of the radial zones, for example, the central heating zone 648 and the edge heating zone 649 are located in the plate portion 605 and completely outside the perimeter of the interior of the hollow shaft 602 . In one embodiment, at least a first temperature sensor or thermocouple 651 is provided in the plate 601 for each central heating zone 647a, 647b; at least a second temperature sensor or thermocouple 652 is provided in the plate 601 for each central Heating zones 648a, 648b, and at least a third temperature sensor or thermocouple 653 are provided in plate 601 for each edge heating zone 649a, 649b. In one embodiment, the temperature sensors are disposed within the confines of their respective heating zones 647a, 647b, 648a, 648b, 649a, 649b when viewed in plan view, as shown in FIG. 17 . In one embodiment, the heating zone in plate 601 is substantially planar and when viewed in plan defines an area for which at least one temperature sensor is located within the area of this heating zone, or in the plane of the heating zone Centered or spaced from this plane along axis 643 . In this way, the temperature sensor is located near the heating zone. In one embodiment, each of the heating zones in plate 601 is substantially planar and extends substantially perpendicular to axis 643 . It should be understood that all or part of the temperature sensors 651 to 653 can be set in this way.

Joining methods according to some embodiments of the present invention rely on controlling the wetting and flow of the joining material relative to the ceramic pieces to be joined. In certain embodiments, oxygen is absent during the joining process to allow for proper wetting without reactions that alter the materials in the joining region. With proper wetting of the joining material and allowing it to flow, a hermetically sealed joint can be obtained at relatively low temperatures. In certain embodiments of the invention, a premetallization of the ceramic is done in the region of the connection before the connection process.

In some applications of end products using joined ceramics, the strength of the joint may not be a critical design factor. In some applications, the hermeticity of the connection may be required to allow separation of the atmosphere on either side of the connection. Also, the composition of the joining material may be important so that it is resistant to chemicals to which the end product of the ceramic component may be exposed. The joining material may need to be resistant to chemicals that could otherwise degrade the joint and compromise the hermetic seal. The joining material may also need to be of a material type that does not negatively interfere with post-processing supported by the final ceramic device.

In some embodiments of the invention, the joined ceramic components are composed of a ceramic such as aluminum nitride. Other materials such as aluminum, silicon nitride, silicon carbide or beryllium oxide may be used. In some aspects, the first ceramic piece can be silicon nitride and the second ceramic piece can be aluminum nitride, zirconia, zirconia, or other ceramics. In some of the present processes, the parts of the joined ceramic assembly may first be made separately in an initial process involving a processing furnace in which the first and second pieces are formed. In some embodiments, a recess may be included in one of the mating pieces, which allows the other mating piece to be located within the recess.

In some embodiments, the connection portion may include a plurality of supports adapted to maintain a minimum solder layer thickness. In some embodiments, one of the ceramic pieces, such as the shaft, may employ multiple support shafts on the end of the shaft to be connected to the plate or multiple support shafts on the surface of the cover to be connected to the plate. The support shaft may be part of the same structure as the ceramic piece and may be formed by mechanically cutting away some of the structure from the ceramic piece, leaving the support shaft. The support shaft may abut against the end of the ceramic piece after the connection process. In some embodiments, a support shaft may be used to create a minimized braze layer thickness for the connection. In some embodiments, the brazing layer material prior to brazing will be thicker than the distance maintained by the supporting shaft or powder particles between the shaft end and the plate. In some embodiments, other methods may be used to establish the minimum solder layer thickness. In some embodiments, ceramic balls may be used to establish a minimum braze layer thickness. In some aspects, the joint thickness may be slightly larger than the size of the support shaft or other minimum thickness determining means, since it is not necessary to squeeze all of the brazing material from between the support and the adjacent contact surface. In some aspects, a portion of the aluminum brazing layer may be found between the support and the adjacent contact surface. In some embodiments, the thickness of the brazing material prior to brazing may be 0.006 inches, with a minimum thickness of 0.004 inches for a complete joint. The brazing material may be aluminum with an iron weight ratio of 0.4Wt.%. In some embodiments, supports may not be used.

In installations where the brazing material is aluminum, the brazing material should be compatible with both types of atmospheres when they are found on both sides across the connection. Aluminum has a self-limiting layer forming alumina. This layer is uniform throughout and once formed prevents or significantly limits other oxygen or other oxidizing chemicals (fluorine chemicals) from penetrating the underlying aluminum and continuing the oxidation process. In this way, there is an initial brief period of oxidation or corrosion of the aluminum, which is then substantially stopped or slowed down by the oxide layer (fluoride layer) that has formed on the surface of the aluminum. The brazing material may be in the form of a sheet, powder, film, or any other form factor suitable for the brazing process described herein. For example, the brazing layer may be a sheet having a thickness between 0.00019 inches and 0.011 inches or more. In some embodiments, the brazing material may be a sheet having a thickness of approximately 0.0012 inches. In some embodiments, the brazing material may be a sheet having a thickness of about 0.006 inches. Typically, alloying constituents in aluminum (eg, magnesium) form as precipitates between grain boundaries of aluminum. Although they can reduce the oxidation resistance of the aluminum bonding layer, usually these precipitates do not form a continuous path through the aluminum and thus do not allow the oxidizing agent to penetrate the full aluminum layer and thus leave the self-limiting oxide layer of aluminum intact , the self-limiting oxide layer of the aluminum provides its corrosion resistance. In embodiments using aluminum alloys comprising constituents capable of forming precipitates, the parameters of processing, including cooling protocols, will be adapted to minimize precipitates in the lattice boundaries. For example, in one embodiment, the brazing material may be aluminum having a purity of at least 99.5%. In some embodiments, commercially available aluminum foil having a purity greater than 92% can be used. In some embodiments, alloys are used. Alloys may include Al-5w%Zr, Al-5w%Ti, industrial alloys #7005, #5083 and #7075. In some embodiments, these alloys may be used at joining temperatures of 1100°C. In some embodiments, these alloys may be used at temperatures between 800°C and 1200°C. In some embodiments, these alloys may be used at lower or higher temperature conditions.

The insensitivity of AIN with aluminum diffusion under the conditions of processing according to embodiments of the invention results in the preservation of the material properties and material density of the ceramic after the brazing step in the manufacture of the plate shaft assembly.

In some embodiments, the ligation process is performed in a process chamber adapted to provide very low pressures. Joining processes according to embodiments of the present invention may require the absence of oxygen for achieving hermetically sealed joints. In some embodiments, the treatment is performed under pressure conditions below 1 x 10E-4 Torr. In certain implementations, the treatment is performed at pressure conditions below 1 x 10E-5 Torr. In certain embodiments, oxygen scavenging is further achieved wherein zirconia or titanium is placed in the processing chamber. For example, a zirconia inner chamber can be placed around the pieces to be joined.

In some embodiments, an atmosphere other than vacuum may be used to achieve a hermetic seal. In some embodiments, an argon (Ar) atmosphere may be used to achieve a hermetic connection. In some embodiments, other inert gases are used to achieve a gas-tight connection. In some embodiments, a hydrogen (H ₂ ) atmosphere may be used to achieve a hermetic connection.

The wetting and flow of the brazing layer is sensitive to several factors. Factors of concern include brazing material composition, ceramic composition, chemical makeup of the atmosphere in the processing chamber (especially oxygen levels in the joining process chamber), temperature, soak time, thickness of the brazing material, thickness of the materials to be joined. The surface features, the geometry of the pieces to be joined, the physical pressure exerted on the joint during the joining process and/or the joint gap maintained during the joining process.

In some embodiments, the surface of the ceramic may undergo metallization prior to placing the ceramic piece in the chamber for connection. In some embodiments, the metallization may be friction metallization. Friction metallization may include the use of aluminum rods. A rotary tool can be used to rotate the aluminum rod over the area that will adjoin the braze layer when joining the pieces. The friction metallization step can leave some aluminum on the surface of the ceramic part. The friction metallization step can modify the ceramic surface to some extent, for example by removing certain oxides, making the surface more suitable for wetting the brazing material. The metallization step is thin film sputtering in some embodiments.

An example of a brazing method for joining together first and second ceramic pieces includes the step of: bonding the first and second ceramic pieces with aluminum Joining together a brazing layer of a group consisting of an aluminum alloy, heating the brazing layer to a temperature of at least 800° C., and cooling the brazing layer to a temperature below its melting point so that the brazing layer hardens and creates air tightness A seal to connect the first member to the second member. Various geometries of brazed joints may be implemented according to the methods described herein.

Connection processing according to some embodiments of the present invention may include some or all of the following steps. Select two or more ceramic pieces for connection. In some embodiments, multiple tie layers may be used to join multiple pieces in the same set of processing steps, but for clarity of discussion, the use of one tie layer to join two ceramic pieces will be discussed here. The ceramic piece may be aluminum nitride. Ceramic parts can be single crystal or polycrystalline aluminum nitride. Portions of each ceramic piece have been identified as areas where each ceramic piece will be connected to each other. In the illustrated embodiment, a portion of the bottom of the ceramic plate structure will be connected to the top of the ceramic hollow cylindrical structure. The connecting material may be a brazing layer including aluminum. In certain embodiments, the brazing layer may be a commercially available aluminum foil having an aluminum content greater than 99%. In some embodiments, the solder layer may consist of multiple layers of foil.

In some embodiments, the specific surface area to be joined will be subjected to a pre-metallization step. The pre-metallization step can be achieved in various ways. In one method friction pre-metallization is used, by using a metal rod of 6061 aluminum alloy that can be rotated with the rotating tool and pressed against the ceramic in the area of the joint so that some aluminum can be deposited in the area of the joint on each of the two ceramic pieces. In another method, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), electroplating processing, plasma spraying or other methods can be used to apply the pre-metallization.

Before joining, the two ceramic pieces may be fixed relative to each other in order to maintain some positional control while in the processing chamber. Fixing also facilitates the application of an applied load to create a contact pressure between the two ceramic pieces and across the connection during the application of temperature. A ballast can be placed on top of the fixed ceramic so that contact pressure is exerted on the connection. The ballast may be proportional to the area of the solder layer. In certain embodiments, the contact pressure exerted on the connection portion acting on the connection portion contact area may be in the range of approximately 2 psi to 500 psi. In certain embodiments, the contact pressure may be in the range of 2 psi to 40 psi. In some embodiments, a minimum pressure may be used. The contact pressure applied in this step is much lower than in the joining step as in prior art processes using hot stamping/sintering which may use pressures in the range of 2000psi to 300psi.

In embodiments using a support shaft as a support or using other methods of joint thickness control such as ceramic balls, the original thickness of the braze layer prior to application of heat may be greater than the height of the support shaft. When the temperature of the brazing layer reaches and exceeds the liquidus temperature, the pressure between the ceramic parts being connected on the brazing layer will cause relative movement between the ceramic parts until the support shaft on the first ceramic part contacts the second ceramic part. until the contact surface. At this point, the contact pressure on the connection will no longer be supplied by external forces (other than the resistance of repulsive forces within the solder layer, if any). Supporting the shaft before the ceramic part has been completely wetted can prevent the solder layer from being pushed out into the connection area and thus can allow better and/or more complete wetting during the connection process. In some embodiments, no support shaft is used.

The stationary assembly can be placed in the processing furnace. The furnace can be evacuated to a pressure of less than 5 x 10E-5 Torr. In some aspects, the vacuum removes the remaining oxygen. In certain embodiments, a vacuum below 1 x 10E-5 Torr is used. In certain embodiments, the fixation assembly is placed within a zirconium inner chamber that acts as an oxygen inducer, further reducing residual oxygen that may have reached the joint during processing. In certain embodiments, the process furnace is purged and refilled with a pure dehydrated pure inert gas, such as argon, to remove oxygen. In certain embodiments, the furnace is purged and refilled with purified hydrogen to remove oxygen.

The fixed assembly is then subjected to the temperature increase and maintained at the connection temperature. When starting the heating cycle, the temperature can be increased slowly, e.g. 15°C per minute to 200°C, thereafter at 20°C per minute to a standard temperature, e.g. 600°C and junction temperature and hold each temperature for a fixed dwell time , to allow vacuum to be restored after heating, for gradient minimization and/or for other reasons. When the brazing temperature has been reached, the temperature can be maintained for the (required) time to effectively carry out the brazing reaction. In an exemplary embodiment, the dwell temperature may be 800°C and the dwell time may be 2 hours. In another exemplary embodiment, the dwell temperature may be 1000°C and the dwell time may be 15 minutes. In another exemplary embodiment, the dwell temperature may be 1150° C. and the dwell time may be 30 to 45 minutes. In some embodiments, the dwell temperature will not exceed a maximum of 1200°C. In some embodiments, the dwell temperature will not exceed a maximum of 1300°C. Where an effective braze dwell time is achieved, the furnace may be cooled at a rate of 20°C per minute or at a slower rate to room temperature when the inherent furnace cooling rate is lower. The furnace may be brought to atmospheric pressure conditions and the open and brazed components may be removed for inspection, characterization and/or evaluation.

Using too high a temperature for too long a period of time may cause voids to form in the connection layer due to significant aluminum evaporation. Since voids are formed in the connection layer, the airtightness of the connection may be lost. The treatment temperature and the treatment temperature holding time can be controlled so that the aluminum layer does not evaporate off and an airtight connection is achieved. , in addition to the other processing parameters mentioned above, a continuous connection can be formed under proper temperature and processing time control. The continuous connection achieved according to the embodiments described herein will result in a hermetic seal, as well as structural attachment.

The brazing material will flow and allow to wet the surface of the ceramic material being brazed. When an aluminum brazing layer is used to join ceramics, such as aluminum nitride, at a sufficiently low oxygen content and as described herein, the connection is a hermetically brazed connection. This is in contrast to the case of diffusion bonding in some existing ceramic joining processes.

In some embodiments, the ceramic parts to be joined can be configured such that no pressure acts on the solder layer during brazing. For example, a post or shaft may be placed into a countersink or recess in a mating ceramic piece. Countersinks can be larger than the outside dimensions of the post or shaft. This can create an area around the post or shaft that can then be filled with aluminum or an aluminum alloy. In this solution, the pressure exerted between the two ceramic parts for holding during connection does not result in any pressure acting on the solder layer. Furthermore, fixing can be used to hold each ceramic piece in a preferred end position such that there is little or no pressure between the ceramic pieces.

Joining assemblies as described above results in components having a hermetic seal between the connected components. Such assemblies can be used in cases where isolation of the atmosphere is an important aspect during use of the assembly. Furthermore, parts of the connection that may be exposed to various atmospheres when the connected components are subsequently used in semiconductor processing will not degrade in such atmospheres nor will they contaminate subsequent semiconductor processing.

Both airtight and non-airtight connections can securely connect pieces since significant force is required to separate the parts. However, the strength of the connection does not depend on whether the connection provides a hermetic seal. The ability to obtain an airtight connection may be related to the wetting of the connection. Wetting describes the ability or tendency of a liquid to disperse on the surface of another material. If there is insufficient wetting in the solder connection, there will be areas where the bond cannot be effected. If there is enough non-wetted area, gas may pass through the connection, causing a leak. At various stages in the process of melting the brazing material, pressure on the joint can affect wetting. Wetting in the junction area can be enhanced by limiting the compression of the braze layer beyond the ceramic minimum distance using support shaft supports or other support means such as inserting ceramic balls or powder particles of appropriate diameter. Careful control of the atmosphere experienced by the brazing elements during the joining process can enhance wetting of the joint region. In combination, careful control of the junction thickness and careful control of the atmosphere used during processing can lead to complete wetting of the junction contact area, which is not achievable in other treatments. Furthermore, in combination with other cited factors, very good wetting, airtightness and connection can result by using a braze layer with an appropriate thickness, which can be greater than the support shaft support height. While different tie layer thicknesses may be successful, an increased thickness of the tie layer may enhance the success rate in terms of airtightness of the connection.

The presence of large amounts of oxygen or nitrogen during the brazing process can lead to reactions that interfere with complete wetting of the joint contact area, which in turn can lead to a leaky joint. Without complete wetting, non-wetting areas are introduced into the final connection in the connection contact region. When enough continuous non-wetting areas are introduced, the airtightness of the connection will be lost.

The presence of nitrogen may cause the nitrogen to react with the molten aluminum to form aluminum nitride, and this reaction formation may interfere with wetting of the joint contact area. Similarly, the presence of oxygen can cause the oxygen to react with the molten aluminum to form alumina, and this reaction formation can interfere with the wetting of the joint contact area. The use of a vacuum atmosphere with a pressure below 5 x 10-5 Torr has been shown to remove enough oxygen and nitrogen to allow full robust wetting of the joint contact area and a hermetic joint. In some embodiments, higher pressures are used, including atmospheric pressure, and the use of non-oxidizing gases, such as hydrogen, or purely inert gases, such as argon, also results in robust wetting, for example in the process chamber during the brazing step. Connection contact area and gas-tight connection. In order to avoid the oxygen reactions mentioned above, the oxygen content in the process chamber must be low enough during the brazing process that it does not negatively affect the complete wetting of the joint contact area. In order to avoid the nitrogen reactions mentioned above, the nitrogen content present in the process chamber during the brazing process must be low enough so as not to negatively affect the complete wetting of the joint contact area.

In combination with maintaining a minimum joint thickness, choosing an appropriate atmosphere during the brazing process can allow for complete wetting of the joint. Conversely, choosing an unsuitable atmosphere can lead to poor wetting, generation of voids and non-airtight connections. A proper combination of controlled atmosphere and controlled joint thickness along with proper material selection and temperature during brazing allows joining materials with a hermetic joint.

In some embodiments of the invention, where one or both of the ceramic surfaces are pre-metallized prior to brazing, for example by sputtering of aluminum films, the joining process step may use lower temperatures held for shorter periods of time. At the start of the heating cycle, the temperature can be increased slowly, e.g., at 15°C per minute to 200°C and then at 20°C per minute to a standard temperature, e.g., 600°C and junction temperature, each held at a constant Dwell time to allow vacuum to be restored after heating for gradient minimization and/or for other reasons. When the brazing temperature has been reached, the temperature can be maintained for the (required) time to effectively carry out the brazing reaction. In some embodiments using one or more of the pre-metallized contact surfaces, the brazing temperature may be in the range of 600°C to 850°C. In an exemplary embodiment, the dwell temperature may be 700°C and the dwell time may be 1 minute. In another exemplary embodiment, the dwell temperature may be 750°C and the dwell time may be 1 minute. Where an effective braze dwell time is achieved, the furnace may be cooled at a rate of 20°C per minute or at a slower rate to room temperature when the inherent furnace cooling rate is lower. The furnace may be brought to atmospheric pressure conditions and the open and brazed components may be removed for inspection, characterization and/or evaluation.

With regard to the aluminum brazing process which does not deposit an aluminum layer onto the contact area of the connection, such a process produces a gas-tight connection at low temperature and with a short dwell time at the brazing temperature, for example The ceramic has a thin layer of aluminum deposited on it using the thin film sputtering technique. Using an aluminum layer deposited on the contact surface may be relatively more convenient and requires less energy to wet the surface, allowing lower temperatures and shorter dwell times to be used to achieve a gas-tight connection.

The process summary for this brazing process is as follows: The joint is between two pieces of polycrystalline aluminum nitride. The braze layer material is 0.003" thick 99.8% aluminum foil. Metallize the junction area of the ring using a thin film deposition of 2 microns thick aluminum. The junction temperature is 780°C and held for 10 minutes. Bonding was performed in the process chamber at a pressure of -5 Torr. 0.004" diameter zirconia balls were used to maintain the bond thickness. The first piece (annular piece) is etched before depositing the thin aluminum layer. The sonographic image of the joint completely shows a solid dark color in the area where the ceramic is well wetted. The connections were found to be of good and sufficient integrity. This connection is airtight. Hermeticity was verified by a vacuum leak rate of less than 1 x 10E-9 sccm He/sec; verification was performed by a standard commercially available helium mass spectrometer leak detector.

Fabricating a multi-zone heater assembly according to an embodiment of the present invention allows insertion of thermocouples after final sintering of the ceramic pieces of the heater, wherein the zones of the heater are monitored with the thermocouples. The thermocouple is also isolated from the external environment to which the heater will be exposed during semiconductor processing, which may include corrosive gases, by a hermetic seal adapted to withstand high temperatures and those corrosive gases. In addition, the hermetic seal is also a structural connection and can structurally connect and hermetically seal the multi-component assembly with one brazing step.

Another advantage of the connection method as described herein is that connections according to some embodiments of the present invention may allow assembly to be disassembled for repair or replacement of one of the two components as needed. Because the joining process cannot modify the ceramic part by diffusing the joining layer into the ceramic, the ceramic part can be reused.

In some embodiments, shaft and plate alignment and position are maintained by part geometry, eliminating fixture and post bond machining. Weighting can be used to ensure that no other motion occurs during the bonding process than some axis motion as the braze material melts. The board can be placed from top to bottom, wherein the connecting elements are located in recesses in the rear surface of the board. The shaft can be inserted vertically down into a recess in the plate. Weights may be placed on the shaft 401 to provide some contact pressure during the joining process.

In some embodiments, the axis/plate position and verticality are maintained by fixing. Mounting may be imprecise due to thermal expansion and machining tolerances, therefore, post bond machining may be required. The shaft diameter can be increased to accommodate the required material removal to meet final size requirements. Also, weighting can be used to ensure that no other motion occurs during the bonding process than some axis motion as the braze material melts. The board can be placed from top to bottom, wherein the connecting elements are located above the rear surface of the board. Shafts can be placed onto plates to create plate and shaft pre-assemblies. A clamp is adapted to support and position the shaft. Clamps can be pinned into the plate to provide positional integrity. Ballast weights can be placed on the shaft to provide some contact pressure during the joining process.

An aspect of the invention is the maximum operating temperature of the bonded shaft-plate as defined by the tensile strength degrading with temperature of the aluminum or aluminum alloy chosen for the connection. For example, if pure aluminum is used as the connection material, the structural strength of the joint between the shaft and the plate becomes extremely low as the temperature of the joint approaches the melting temperature of aluminum (typically 660°C). In practice, when using 99.5% or pure aluminum, the shaft-plate assembly will withstand all normal and expected stresses encountered in a typical silicon wafer processing tool for a temperature of 600°C. However, certain semiconductor device processes require temperatures greater than 600°C.

A service procedure may be implemented as follows for disconnecting components that have been connected according to embodiments of the present invention. Such an assembly may be placed in a processing furnace using a clamp adapted to apply tension on the connection. Fixing may apply a tensile stress of approximately 2 psi to 30 psi to the joint contact area. In some embodiments, fixation can place greater stress on the connection. The fixed assembly can then be placed in a processing furnace. The furnace can be vented, although venting may not be required during these steps. The temperature is increased slowly, eg, 15°C per minute to 200°C, followed by 20°C per minute to a standard temperature, eg, 400°C, and then to the split temperature. Upon reaching the separation temperature, the pieces can be separated from each other. The separation temperature is specific to the materials used in the brazing layer. In some embodiments, the separation temperature may range from 600°C to 800°C. The fixation may be adapted to allow limited movement between the two pieces so that the pieces are not damaged when separated. The separation temperature can be material specific. For aluminum, the separation temperature may range from 450°C to 660°C.

Before reusing a previously used piece, eg a ceramic shaft, the piece may be prepared for reuse by machining the connection area to remove irregularities. In some embodiments, it is desirable to remove all remaining brazing material so that the total amount of brazing material in the connection is controlled when the piece is connected to a new mating part.

In contrast to joining methods that create a diffusion layer within the ceramic, the joining process according to some embodiments of the invention does not result in such a diffusion layer. Thus, the ceramic and brazing material retains the same material properties after the brazing step as before the brazing step. Therefore, if a part needs to be reused after separation, the same material and the same material properties should be present in the part to allow reuse under conditions of known composition and properties.

In one embodiment, a wafer holder for use in semiconductor processing is provided and can include: a shaft having an axis and an end; a plate connected to the shaft an end portion and having a portion extending radially outward from the axis beyond the shaft; a temperature sensor disposed in the portion of the plate; and an electrical lead extending from the temperature sensor through the shaft, for measuring the temperature of the board in the vicinity of a temperature sensor during semiconductor processing.

The plate can be a ceramic plate. The wafer clip can also comprise an additional temperature sensor arranged at a radial distance from the temperature sensor in said portion of the board; and an additional electrical lead from the additional temperature sensor. A sensor extends through the shaft for measuring the temperature of the plate in the vicinity of an additional temperature sensor. The wafer holder can further comprise: a first heater for heating the plate near the temperature sensor; and a second heater for heating the plate near the additional temperature sensor independently of the first heater. The panel can be formed from at least a first ply and an adjacent second ply, the second ply being hermetically connected to the first ply, the first ply having a first surface, the second ply The layer has a second surface opposite the first surface, at least one of the first and second surfaces having a recess therein for forming a temperature sensor between the first ply and the second ply and a recess extending between the shaft for receiving an electrical lead. The recess can include: a first channel for receiving an electrical lead; and a second channel for receiving an additional electrical lead. The recess can comprise a cylindrical cavity centered on said axis. The silicon wafer clip can also include a connection layer, which is arranged between the first board layer and the second board layer, and is used to airtightly connect the board layers together. The temperature sensor can be a thermocouple.

In one embodiment, a multi-zone heater is provided and can include a heating plate that includes a first heater that can be a distance from the center of the heating plate A radial distance; a first thermocouple sleeve, the first thermocouple sleeve is located within the range of the first radial distance; a first thermocouple, the first thermocouple is located at the first thermocouple Inside the casing; a second heater positioned at a range of a second radial distance from the center of the heating plate, wherein the second radial distance is greater than the area of the first radial distance The range of distances is farther from the center of the heating plate; and a second thermocouple well, the second thermocouple well is located within the range of the second radial distance; a second thermocouple, the second thermocouple is located within the second thermocouple well; a channel between the heating plate and the cover; and a cover over the channel, wherein the second thermocouple includes a telemetry lead shunted through the channel.

The multi-zone heater can also include a hollow heating shaft attached to the heating plate, the hollow heating shaft comprising an inner surface and an outer surface. The second thermowell can be located in the heating plate outside the area enclosed by the interior of the hollow heating shaft. The telemetry lead of the second thermocouple can be shunted through the channel into the interior of the hollow heated shaft. The lid can be connected gas-tight to the heating plate by means of the first connection layer. The heating plate can comprise aluminum nitride. The hollow heated shaft can comprise aluminum nitride. The first connection layer can comprise aluminum. The multi-zone heater can further comprise a second tie layer disposed between the heating plate and the hollow heating shaft, wherein the second tie layer hermetically seals the The interior space is isolated from the exterior of the shaft by the second connection layer. The second connection layer can comprise aluminum.

In one embodiment, a multi-zone heater is provided and can include a multi-layer heating plate that can include: a top plate layer; one or more middle plate layers; a bottom plate layer and a plurality of plate connection layers arranged between the respective plate layers, wherein the connection layer connects the respective plate layers; a plurality of heating elements positioned between the two plate layers zones, the heating element zones adapted to be individually controlled; and a plurality of thermocouples mounted between two of the plies.

Thermocouples can be positioned at various distances from the center of the multilayer heating plate. The multi-zone heater can also include a hollow heating shaft attached to the bottom surface of the multi-layer heating plate. The thermocouple can include thermocouple wires, and the thermocouple wires can shunt through the interior of the hollow heated shaft. One or more of said thermocouples can be located outside the area enclosed by the shaft attached to the multilayer plate. The multi-zone heater can also include a tie layer between the hollow heating shaft and the multilayer plate. The plurality of board connection layers can comprise aluminum. The connecting layer between the hollow heating shaft and the multilayer plate can comprise aluminium. The top layer and the bottom layer can comprise ceramics. The hollow heating shaft can comprise aluminium. The plurality of board connection layers can comprise aluminum. The connecting layer between the hollow heating shaft and the multilayer plate can comprise aluminium. The multi-zone heater can also include a central liner disposed between the hollow heating shaft and the multilayer plate.

From the above description it is apparent that various embodiments can be constructed by the description given herein, and further advantages and modifications are readily apparent to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit and scope of applicant's subject invention.

Claims (9)

1. a kind of wafer chuck for being used in manufacture of semiconductor, including：Axle, the axle have axis and end；Plate, it is described Plate is connected to the end of the axle and set with the part that the axle is extended radially outward beyond from the axis, the plate There is the recess extended in the part；Temperature sensor, the temperature sensor are arranged in the part of the plate；With And electrical lead, the electrical lead extends through the recess and the axle from the temperature sensor, in semiconductor system Temperature of the plate near the temperature sensor is measured during journey, it is characterised in that high by the percentage by weight by aluminium Aluminium connecting portion made of aluminium soldering element in 92%, the recess hermetic seal off with corrosive process gases, and And the plate is free of diffusion layer around the aluminium connecting portion.

2. wafer chuck according to claim 1, wherein, the plate is ceramic wafer.

3. wafer chuck according to claim 1, in addition to：Additional temperature sensor, the additional temperature sensor and institute Temperature sensor is stated to be arranged at a distance of certain radial distance in the part of the plate；And additional electrical lead, it is described attached Power-up lead extends through the axle from the additional temperature sensor, is sensed for measuring the plate in the additional temp Temperature near device.

4. wafer chuck according to claim 3, in addition to：Primary heater, the primary heater are used in the temperature Spend sensor proximity and heat the plate；And secondary heater, the secondary heater are used for independently of the primary heater The plate is heated near the additional temperature sensor in ground.

5. wafer chuck according to claim 3, wherein, the plate is by least the first flaggy and the second flaggy shape adjoined Into second flaggy is hermetic connected to first flaggy, and first flaggy has first surface, second plate Layer has a second surface relative with the first surface, and at least one in the first surface and second surface has wherein There is recess, extend for being formed between first flaggy and the second flaggy between the temperature sensor and the axle Be used for receive the recess of the electrical lead.

6. wafer chuck according to claim 5, wherein, the recess includes：First for receiving the electrical lead is logical Road；With the second channel for receiving the additional electrical lead.

7. wafer chuck according to claim 5, wherein, the recess includes the cylindrical chamber centered on the axis.

8. wafer chuck according to claim 1, wherein, the aluminium connecting portion is by the way that aluminium soldering element is heated at least 800 DEG C of temperature and the aluminium connecting portion formed.

9. wafer chuck according to claim 1, wherein, the temperature sensor is thermocouple.