HOLD FOR HIGH-PERFORMANCE LAMPS FOR A RAPID HEATING OVEN

Description

[0001] This patent application claims priority from French patent application FR22 / 05604, which will be considered as forming an integral part of this description. technical field

[0002] This description relates generally to high-intensity lamp holders for rapid thermal annealing furnaces and rapid thermal annealing furnaces comprising such holders. Previous technique

[0003] A rapid thermal annealing furnace is a furnace that allows an object, particularly a silicon substrate, to be brought to a high temperature, for example up to 1200 °C or more, in a very short time, generally a few seconds.

[0004] Such temperature increases are achieved using high-intensity lamps or laser heating. In the case of high-intensity lamps, particularly infrared lamps, the furnace includes a lamp holder. This holder has a wall facing the lamps, designed to reflect the radiation emitted by the lamps back towards the object to be heated. It is also generally necessary to provide a cooling system for the holder, for example, a water circulation system within internal channels.

[0005] It is known to produce a high-intensity lamp holder for a rapid thermal annealing furnace using aluminum parts assembled with screws and cooled by water. One drawback is that the water circulation can cause corrosion of the aluminum, necessitating maintenance to replace parts of the holder. US patent 8,698,049 describes a high-intensity lamp holder. Summary of the invention

[0006] An object of an embodiment is to provide a high-intensity lamp holder for a rapid thermal annealing furnace, overcoming all or part of the disadvantages of existing high-intensity lamp holders.

[0007] Another object of an embodiment is that the manufacturing process for the high-intensity lamp holder is simple.

[0008] Another objective of one embodiment is that the manufacturing cost of the high-intensity lamp holder is reduced.

[0009] Another objective of one embodiment is that the maintenance cost of the high-intensity lamp holder is reduced.

[0010] Another object of one embodiment is that the support includes a wall adapted to reflect the radiation emitted by the lamps.

[0011] Another object of one embodiment is that the support incorporates channels for the circulation of a coolant.

[0012] One embodiment provides a support for high-intensity lamps comprising: a first piece of a first material, intended to support the high-intensity lamps and comprising a face intended to be opposite the high-intensity lamps; a second piece of a second material, different from the first material, covering the first piece and fixed to the first piece; and a sheet, of a third material different from the first material, interposed between the first piece and the second piece and delimiting with the second piece at least one cavity intended to contain a coolant.

[0013] According to one embodiment, the second and third materials are stainless.

[0014] According to one embodiment, the second and third materials are less good conductors of heat than the first material.

[0015] According to one embodiment, the first material is included in the group comprising aluminium, copper and copper alloys such as brass.

[0016] According to one embodiment, the second material is included in the group comprising stainless steel, plastics resistant to temperatures above 100 °C, and composite materials resistant to temperatures above 100 °C.

[0017] According to one embodiment, the third material is included in the group comprising stainless steel, copper and copper alloys such as brass.

[0018] According to one embodiment, the thickness of the sheet is between 0.03 mm and 0.3 mm.

[0019] One embodiment also provides for a rapid thermal annealing furnace comprising high-intensity lamps and a support for said high-intensity lamps as defined previously.

[0020] According to one embodiment, high-intensity lamps are infrared lamps.

[0021] According to one embodiment, the oven includes a system for circulating the coolant in the cavity.

[0022] According to one embodiment, the coolant comprises water. Brief description of the drawings

[0023] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the attached figures, among which: there figure 1 is a partial and highly schematic cross-sectional view of an example of a rapid thermal annealing furnace; the figure 2is a partial, schematic cross-sectional view of an example of a high-intensity lamp holder for a rapid thermal annealing furnace; the figure 3 is a partial, schematic cross-sectional view of an embodiment of a high-intensity lamp holder for a rapid thermal annealing furnace; and the figure 4 is an exploded view of the embodiment of the support of the figure 3 . Description of the implementation methods

[0024] The same elements have been designated by the same reference numerals in the different figures. In particular, structural and / or functional elements common to the different embodiments may have the same reference numerals and may possess identical structural, dimensional, and material properties. For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and are detailed.

[0025] Unless otherwise specified, the expressions "approximately," "roughly," "about," and "in the order of" mean within 10%, preferably within 5%. Unless otherwise specified, ordinal numeral adjectives, such as "first," "second," etc., are used only to distinguish elements from one another. In particular, these adjectives do not restrict the described realizations to a specific order of these elements.

[0026] There figure 1 is a partial and schematic cross-sectional view of an example of a 10 rapid thermal annealing furnace.

[0027] The furnace 10 includes a chamber 12, also called a reactor, in which the object 14 to be treated is placed on a support 16. The object 14 to be treated is, for example, a silicon substrate. An inert gas can be injected into the internal volume 18 of the reactor 12 by means of an injection system 20. The internal volume 18 of the reactor 12 can be maintained at low pressure by means of a pumping system 22. The object 14 to be treated is heated by the radiation emitted by high-intensity lamps 24 held by a support 30. The high-intensity lamps 24 are, for example, infrared lamps.

[0028] A quartz window 26 ensures the sealing of the internal volume 18 of the reactor 12 while allowing the IR radiation emitted by the lamps 24 to pass through. The support 30 is further adapted to reflect the IR radiation emitted by the lamps 24 back towards the window 26. The walls of the reactor 12 are cooled, in particular to prevent contamination of the substrate 14 and to protect the control and / or measurement equipment fitted to the reactor 12. The temperature of the substrate 14 can be controlled by a regulator connected to a pyrometer 28.

[0029] There figure 2 is a partial and schematic cross-sectional view of an example of the support 30 for the lamps 24, only one lamp 24 being visible in figure 2 The cross-section plan of the figure 2 is orthogonal to the cutting plane of the figure 1The support 30 consists of a first part 32 and a second part 34, fixed to each other by means of screws 36. Preferably, there are no welds between the first part 32 and the second part 34.

[0030] The lamps 24 are fixed to the first part 32. The first part 32 includes, for example, for each lamp 24, two openings 38 in which the ends of the lamp 24 are housed. The first part 32 includes a wall 40 facing the lamps 24 and which forms a mirror reflecting the radiation emitted by the lamps 24.

[0031] When parts 32 and 34 are assembled, they define internal cavities 42 through which a coolant, for example water, is circulated. These internal cavities 42 can be defined by recesses 44 in the first part 32, which are closed by a flat face 46 of the second part 34 when the second part 34 is assembled to the first part 32.

[0032] The first part 32 may include grooves 48 on the side of the second part 34. The sealing of the internal cavities 42 may be achieved by O-rings 50 arranged in the grooves 48.

[0033] When the lamps 24 are infrared lamps, parts 32 and 34 can be made of aluminum, which is a low-cost material, a good conductor of heat, and a good reflector of the infrared radiation emitted by the lamps 24.

[0034] One drawback is that parts 32 and 34 can corrode from contact with the coolant circulating in the cavities 42 when it contains water. One possibility would be to apply an anti-corrosion treatment to the walls of the cavities 42. However, this tends to complicate the manufacturing process of the support 30 and increases its manufacturing cost.

[0035] There figure 3 is a partial and schematic cross-sectional view of an embodiment of a lamp holder 60 for lamps 24 that can be used as a support 30 for the oven 1 shown in figure 1 . There figure 4 is an exploded view with cross-section of the embodiment of support 60 of the figure 3 The cross-section plan of the figures 3 and 4 is orthogonal to the cutting plane of the figure 1 Only one 24-lamp is visible on the figures 3 and 4 .

[0036] The support 60 comprises a stack of a first part 62, a sheet 90 and a second part 64, fixed to each other by means of screws 66, three screws being shown as an example on the figures 3 and 4 The sheet 90 is sandwiched between the first part 62 and the second part 64. Preferably, there are no welds between the first part 62, the second part 64, and the sheet 90.

[0037] The first part 62 comprises a portion 63, generally square or rectangular in cross-section, with a central axis D, extending into a peripheral rim 65 that extends on the side opposite the second part 64. The lamps 24 are fixed to the rim 65 of the first part 62. The rim 65 of the first part 62 comprises, for example, for each lamp 24, two openings 68 in which the ends of the lamp 24 are housed. The first part 62 comprises a wall 70 facing the lamps 24 and forming a mirror that reflects the radiation emitted by the lamps 24. In one embodiment, the wall 70 comprises a flat area of ​​square or rectangular shape at the central part 63 of the first part 62, and comprises square or rectangular areas at the rim 65.The first part 62 includes a face 71 located on the side of the sheet 90 and against which the sheet 90 is applied when the first part 62, the sheet 90, and the second part 64 are fastened to each other by means of the screws 66. In one embodiment, the face 71 is flat and the sheet 90 is flat. In another embodiment, the face 71 is square or rectangular.

[0038] When assembled, parts 62, 64, and the sheet 90 define internal cavities 72 through which a coolant, for example, water possibly containing additives, is circulated during operation. The internal cavities 72 are defined by recesses 74 in the second part 64, which are sealed by the sheet 90 when the second part 64 is assembled to the first part 62 with the sheet 90 in between. The second part 64 has grooves 78 on the side facing the first part 62. The internal cavities 72 can be sealed by O-rings 80 positioned in the grooves 78.

[0039] The first part 62 is made of a first material. In one embodiment, the first material is included in the group comprising aluminum, aluminum alloys with good mirror-like mechanical polishing properties, copper, and copper alloys such as brass. The surface 70, which acts as a mirror to the radiation from the lamps 24, can be easily obtained by mechanical polishing without the need to apply a reflective coating to the surface 70. In one embodiment, the surface roughness Ra of the surface 70 is less than 0.2. In another embodiment, the surface 70 reflects more than 90% of the radiation emitted by the lamps 24. In another embodiment, the radiation emitted by the lamps 24 has a wavelength between 0.5 µm and 4 µm, preferably with an emission peak at 1 µm for a filament temperature of 2500 K.

[0040] The average thickness of the first part 62 in the areas facing the cavities 72 is between 4 mm and 8 mm. In one embodiment, the thickness of the peripheral rim 65 of the first part 62, measured along axis D, is between 10 mm and 20 mm. Since the first material is a good conductor of heat, it allows efficient dissipation of the heat transmitted to the first part 62 by the lamps 24 into the coolant without the need for cavities for the circulation of the coolant directly in the rim 65 of the first part 62.

[0041] The second part 64 is made of a second material different from the first material. The second material is stainless. The second material may be a less good conductor of heat than the first material. In one embodiment, the second material is included in the group comprising stainless steel, plastics resistant to temperatures above 100 °C, in particular polyoxymethylene-based thermoplastics, and composite materials resistant to temperatures above 100 °C. The depth of each indentation 74, measured along axis D, may be between 5 mm and 10 mm.

[0042] The sheet 90 is made of a third material that is different from the first material and possibly identical to the second material. The third material is stainless. The third material may be a less good conductor of heat than the first material, but is preferably metallic to ensure sufficient heat conduction. In one embodiment, the third material is included in the group comprising stainless steel, copper, and copper alloys such as brass. In one embodiment, the thickness of the sheet 90 is less than 0.5 mm, preferably between 0.03 mm and 0.3 mm. The reduced thickness of the sheet 90 allows it to be easily deformed.

[0043] According to one embodiment, the sheet 90 completely covers the face 71 of the first piece 62. In the case where the face 71 corresponds to a square or a rectangle, the sheet 90 corresponds to a square or a rectangle of the same area.

[0044] During operation, the coolant only comes into contact with stainless materials. This advantageously prevents corrosion of the support 60, particularly when the coolant is water-based. Furthermore, anti-corrosion treatment of the cavity walls 72 is unnecessary. The manufacturing process for the support 60 therefore remains simple.

[0045] During operation, the coolant in the cavities 72 is pressurized and holds the sheet 90 against the first part 62. This results in direct contact between the sheet 90 and the first part 62, virtually without an intervening air film. Therefore, good heat transfer between the first part 62 and the sheet 90 is achieved. In one embodiment, the pressure of the coolant in the cavities 72 is between 0.1 MPa and 0.5 MPa, preferably between 0.3 MPa and 0.4 MPa.Furthermore, given the reduced thickness of the sheet 90, even if the sheet 90 is made of a third material that is a less good conductor of heat than the first material composing the first part 62, the third material being nevertheless preferably metallic, the conduction of heat between the first part 62 and the coolant through the very thin sheet 90 is sufficiently efficient to allow adequate cooling of the first part 62 in operation.

[0046] Various embodiments and variants have been described.

[0047] Finally, the practical implementation of the described embodiments and variants is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

1. Holder (60) for high-intensity lamps (24) comprising: - a first part (62) made of a first material, intended to support the high-intensity lamps and comprising a surface (70) intended to face the high-intensity lamps; - a second part (64) made of a second material, different from the first material, covering the first part and attached to the first part; and - a sheet (90), made of a third material different from the first material, interposed between the first part and the second part and delimiting with the second part at least one cavity (72) intended to contain a coolant.

2. Holder according to claim 1, wherein the second and third materials are stainless.

3. Holder according to claim 1 or 2, wherein the second and third materials are poorer heat conductors than the first material.

4. Holder according to any of claims 1 to 3, wherein the first material is comprised in the group comprising aluminum, copper, and copper alloys such as brass.

5. Holder according to any of claims 1 to 4, wherein the second material is comprised in the group comprising stainless steel, plastics resistant to temperatures higher than 100°C, and composite materials resistant to temperatures higher than 100°C.

6. Holder according to any of claims 1 to 5, wherein the third material is comprised in the group comprising stainless steel, copper, and copper alloys such as brass.

7. Holder according to any of claims 1 to 6, wherein the thickness of the sheet (90) is in the range from 0.03 mm to 0.3 mm.

8. Rapid thermal annealing furnace comprising high-intensity lamps (24) and a holder(60) for said high-intensity lamps according to any of claims 1 to 7.

9. Rapid thermal annealing furnace according to claim 8, wherein the high-intensity lamps (24) are infrared lamps.

10. Rapid thermal annealing furnace according to claim 8 or 9, comprising a system for circulating the coolant in the cavity (72).

11. Rapid thermal annealing furnace according to claim 8, wherein the coolant comprises water.