JP2012503311A - Control of heat during substrate annealing - Google Patents

Abstract

  Methods and apparatus for processing a substrate are provided. The substrate is positioned on a support in the heat treatment chamber. In order to anneal a portion of the substrate, electromagnetic radiation is induced toward the substrate. Other electromagnetic radiation is induced towards the substrate to preheat a portion of the substrate. Preheating reduces the thermal stress at the boundary between the preheat region and the anneal region. Any number of anneal and preheat regions with various shapes and temperature profiles are contemplated as needed for a particular embodiment. Any convenient source of electromagnetic radiation can be used, such as a laser, heat lamp, white light lamp, or flash lamp.

Description

  Embodiments of the invention relate to a method of manufacturing a semiconductor device. More particularly, embodiments of the present invention are directed to a method of thermally processing a substrate.

  The integrated circuit (IC) market is constantly seeking greater memory capacity, faster switching speeds, and smaller feature dimensions. One of the major steps the industry has taken to address these requirements is to change from batch processing of silicon wafers in a large furnace to single wafer processing in a small chamber. .

  During such single wafer processing, the wafer is typically heated to an elevated temperature so that various chemical and physical reactions can occur within a plurality of IC devices defined in the wafer. Of particular importance is that the preferred electrical performance of the IC device requires that the implanted region be annealed. Annealing reproduces additional crystal structures from previously amorphous regions of the wafer and activates the dopants by incorporating dopant atoms into the crystal lattice of the substrate or wafer. In thermal processing such as annealing, it is necessary to provide a relatively large amount of thermal energy to the wafer in a short time, and then rapidly cool the wafer to finish the thermal processing. Examples of thermal processing currently in use include rapid thermal processing (RTP) and impulse (spike) annealing. Although such processing is widely used, current technology is not ideal for large substrates that tend to be exposed to high temperatures for extended periods of time. These problems become more serious with increasing switching speed and / or reducing feature dimensions.

  In general, in these thermal processing, the substrate is heated under controlled conditions according to a predetermined thermal recipe. These thermal recipes basically consist of the temperature at which the semiconductor substrate must be heated at a rate of temperature change, i.e., a temperature ramp up and ramp down rate, and the time during which the thermal processing system is maintained at a particular temperature. For example, in some thermal recipes, the entire substrate may need to be heated from room temperature to a temperature of 400 ° C. or higher for a processing time that exceeds the amount of heat of the device formed on the substrate.

  In addition, the amount of time each semiconductor substrate is exposed to elevated temperatures must be constrained to meet certain objectives, such as minimizing material interdiffusion between different regions of the semiconductor substrate. In order to realize this, it is preferable that both the ramp-up rate and the ramp-down rate of the temperature are high. In other words, it is desirable that the temperature of the substrate can be adjusted from a low temperature to a high temperature or vice versa in the shortest possible time.

  The requirement for a high temperature ramp rate leads to the development of rapid thermal processing (RTP), with typical temperature ramp-up rates of 200-400 ° C./sec compared to 5-15 ° C./min for conventional furnaces. It is a range. Typical ramp-down rates are in the range of 80-150 ° C./second. The disadvantage of RTP is that the entire wafer is heated even if the IC device is only on the top few microns of the silicon wafer. This limits how fast the wafer can be heated and cooled. Furthermore, after the entire wafer is hot, heat can only be dissipated into the surrounding space or structure. As a result, today's state-of-the-art RTP systems struggle to achieve a ramp-up rate of 400 ° C./sec and a ramp-down rate of 150 ° C./sec.

  As device dimensions on the substrate become smaller in the future, the amount of heat must be reduced as well, as smaller devices can be more easily degraded by interdiffusion of materials. In order to compress the annealing time to, for example, less than 1 second, the temperature ramp-up and ramp-down rates must be increased.

  In order to solve some of the problems posed in conventional RTP type processing, various scanning laser annealing techniques have been used to anneal the surface (s) of the substrate. In general, these techniques translate or scan the substrate relative to the energy delivered to the small area while delivering a constant energy flux to the small area on the surface of the substrate. In other laser scanning processes, the substrate is held stationary and the laser is moved across the substrate surface. Because of the strict uniformity requirements and the complexity of minimizing the overlap of the scanned area across the substrate surface, these types of processing allow contact-level devices formed on the surface of the substrate. Not effective for thermal processing. In addition, the thermal stresses generated in the substrate by the high thermal gradients associated with extreme local heating can result in substrate damage.

  In view of the above, there is a need for new apparatus and methods for annealing semiconductor substrates with high ramp-up and ramp-down rates. This provides greater control over the fabrication of smaller devices and results in increased performance.

  Embodiments of the present invention generally provide a method for processing a substrate. One aspect of the present invention is a method of processing a substrate comprising positioning a substrate on a movable substrate support and a first quantity toward a first fixed position below a portion of the substrate. A second amount of heating energy toward a second fixed position below a portion of the substrate, moving the substrate support to the first fixed position, then Processing the selected region of the substrate by sequentially positioning each selected region over the second fixed position and maintaining a portion of the substrate at a temperature below 500 degrees Celsius. I will provide a.

  Another embodiment is a method of processing a substrate, wherein the substrate is positioned on a stationary substrate support, and heating energy is induced toward the substrate to cause at least one hot section on the substrate surface and Forming at least one anneal zone, and processing the selected region of the substrate by moving the heating energy and sequentially positioning the hot zone and then the anneal zone over each selected region. A method of including is provided.

  Another embodiment is an apparatus for heat treating a substrate, wherein the first energy is oriented to induce annealing energy toward the movable substrate support and the first portion of the surface of the substrate support. An apparatus comprising: a source; a second energy source oriented to induce preheating energy toward a second portion of the surface of the substrate support; and an optical assembly containing the first and second energy sources I will provide a.

  Another embodiment is an apparatus for heat treating a substrate that induces annealing energy toward a stationary substrate support and a first portion of the surface of the substrate support, and a second of the surface of the substrate support. One or more energy sources oriented to induce preheating energy towards the portion, an optical assembly containing the one or more energy sources, and annealing energy and preheating energy for a fixed substrate support And an actuator for moving the device.

  The present invention, briefly summarized above, can be more specifically described with reference to the embodiments so that the above features of the present invention can be understood in detail. Some of the embodiments are illustrated in the accompanying drawings. However, since other equally effective embodiments of the present invention are recognized, the accompanying drawings only illustrate exemplary embodiments of the present invention and therefore should not be construed as limiting the scope of the invention. Please note that.

1 is a schematic isometric view of an apparatus according to an embodiment of the invention. 1B is a schematic bottom view of one embodiment of the energy source of FIG. 1A. FIG. FIG. 6 is a schematic isometric view of an apparatus according to another embodiment of the invention. It is a graph of the relationship between the temperature and the position on the substrate being subjected to processing according to an embodiment of the present invention. FIG. 3 is a schematic top view of a substrate that has been subjected to processing according to two embodiments of the present invention. FIG. 3 is a schematic top view of a substrate that has been subjected to processing according to two embodiments of the present invention. 1 is a schematic side view of an apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view illustrating a processing chamber according to an embodiment of the present invention. 1 is a schematic top view of a substrate being processed according to an embodiment of the present invention. 1 is a schematic cross-sectional view illustrating a processing chamber according to an embodiment of the present invention. It is a graph of the relationship between temperature and time on a substrate being subjected to processing according to an embodiment of the present invention. It is a graph of the temperature on the board | substrate currently subjected to the process by embodiment of this invention, and the relationship of time. 5 is a flow diagram summarizing a method according to an embodiment of the invention. 6 is a flow diagram summarizing a method according to another embodiment of the invention. 6 is a flow diagram summarizing a method according to another embodiment of the invention.

  To facilitate understanding, identical reference numerals have been used, where possible, to refer to identical elements that are common to multiple figures. It is contemplated that it would be beneficial for elements disclosed in one embodiment to be available on other embodiments without specific description.

  As device dimensions on a substrate become smaller and as the substrate itself becomes larger, it becomes increasingly impractical to perform a heat treatment on the entire substrate at once. Similar to the potential for non-uniform processing, the power required to energize the entire surface is also very high. Accordingly, a thermal processing apparatus such as an RTP chamber may be configured to sequentially process a portion of the substrate surface. An exemplary thermal processing apparatus such as the DSA® chamber available from Applied Materials, Inc., Santa Clara, California can be used to irradiate a small portion of the substrate surface with laser light to anneal the surface. . At the edge of the laser beam, the substrate surface can be heated at an extreme rate, and the temperature gradient between the irradiated and untreated areas can cause damaging thermal stresses in the substrate. is there. For this reason, the substrate is typically placed on a heated chuck that maintains the entire substrate at an elevated ambient temperature to reduce the stress heating to the annealing temperature. However, the requirement of maintaining the substrate at high temperatures often reduces the benefits of heat treatment. Embodiments of the present invention generally contemplate an improved method of heat treating a substrate.

  In general, the term “substrate” as used herein can refer to any material having some natural conducting ability or an article formed from a material that can be modified to provide the ability to conduct electricity. Typical substrate materials include, but are not limited to, semiconductors such as silicon (Si) and germanium (Ge), and other compounds that exhibit semiconducting properties. Such semiconductor compounds typically include Group III-V and Group II-VI compounds. Exemplary Group III-V semiconductor compounds include, but are not limited to, gallium arsenide (GaAs), gallium phosphide (GaP), and gallium nitride (GaN). Usually, the term “semiconductor substrate” includes bulk semiconductor substrates as well as substrates with deposited layers disposed thereon. Thus, deposited layers in some semiconductor substrates that are processed by the method of the present invention are formed by homoepitaxial (eg, silicon on silicon) or heteroepitaxial (eg, GaAs on silicon) growth. For example, the method of the present invention can be used with gallium arsenide and gallium nitride substrates formed by heteroepitaxial methods. Similarly, by applying the method of the present invention, an integrated device such as a thin film transistor (TFT) is formed on a relatively thin crystalline silicon layer formed on an insulating substrate (eg, a silicon-on-insulator [SOI] substrate). It can also be formed.

  Some embodiments of the present invention provide a method of heat treating a substrate. FIG. 1A is a schematic isometric view of an apparatus 100 according to one embodiment of the present invention. FIG. 1A is characterized in that the energy source 102 is adapted to project an amount of energy onto a defined region or anneal region 104 of the substrate 106 disposed on the work surface 108. The amount of energy projected onto the anneal region 104 is selected to anneal the surface of the substrate 106. In some embodiments, the energy delivered by the energy source is less than that required to melt a portion of the substrate 106. In other embodiments, the energy delivered is selected to preferentially melt a portion of the substrate 106.

  In some embodiments, the energy source 102 comprises a plurality of radiators, as shown schematically in FIG. 1B, and the radiators 102A-102E are shown embedded within the energy source 102. Radiators 102A-102E typically emit radiation that is directed onto substrate 106. In some embodiments, each of the radiators 102A-102E emits the same amount of energy. In other embodiments, the radiators 102A-102E can emit different amounts of energy. In one exemplary embodiment, the radiator 102A can emit an amount of energy selected to anneal the anneal region 104 of the substrate 106, and the radiators 102B-102E are annealed out of the substrate 106. Release a selected amount of energy to preheat one or more portions adjacent, adjacent, or overlapping region 104.

  In one example, as shown in FIG. 1A, at any given time, only one defined region of the substrate, such as the anneal region 104, is exposed to radiation from the energy source. In one aspect of the invention, multiple regions of the substrate 106 are sequentially exposed to the desired amount of energy delivered from the energy source 102 so as to preferentially melt the desired region of the substrate. In another aspect, multiple regions of the substrate 106 are sequentially exposed to an amount of energy from the energy source 102 selected to anneal without melting the desired region of the substrate.

  In general, the area on the surface of the substrate translates the substrate relative to the output of the electromagnetic radiation source (eg, conventional X / Y stage, precision stage) and / or the output of the radiation source relative to the substrate. Can be exposed in sequence by moving them in parallel. Typically, one or more conventional electric actuators 110 (eg, linear DC servo motors, lead screws, and servo motors) are used to control the movement and position of the substrate 106. The electric actuator 110 can be part of a separate precision stage (not shown). A conventional precision stage that can be used to support and position the substrate 106 is available from Parker Hannifin Corporation, Rohnert Park, California.

  In other embodiments, the electromagnetic radiation source can be translated relative to the substrate. For example, in the embodiment of FIG. 1A, the energy source 102 can be coupled to a positioning device (not shown) such as a Cartesian frame adapted to position the energy source 102 over a desired area of the substrate 106. . The positioning device can be further configured to adjust the height of the energy source on the substrate 106.

  Referring again to FIG. 1A, a preheat region 112 is defined on the surface of the substrate 106. In some embodiments, the preheat region 112 surrounds the anneal region 104. In other embodiments, the preheat region can be adjacent to the anneal region 104 or can overlap the anneal region 104. In still other embodiments, the preheat region 112 can be proximate to the anneal region 104, creating a gap or space between the preheat region 112 and the anneal region 104. In some embodiments, the preheat region can be spaced from the anneal region. Thus, the preheat zone can have any convenient shape, such as the circular preheat zone 112 shown in the embodiment of FIG. 1A.

  FIG. 2 is a schematic isometric view of an apparatus 200 according to another embodiment of the present invention. An energy source 202 is configured to direct energy toward a substrate 204 disposed on the work surface 206. In some embodiments, the energy source 202 comprises a plurality of radiators 202A that emit electromagnetic energy of a property selected to heat treat the surface of the substrate 204. At least one of the radiators 202A can be adapted to anneal the annealed portion 208 of the substrate 204, and at least one of the radiators 202A is adapted to preheat the preheated portion 210 of the substrate 204. In the embodiment of FIG. 2, the preheated portion 210 is shown adjacent to the annealed portion 208. Other embodiments may be characterized in that the preheat portion 210 overlaps or is spaced from the anneal portion 208.

  FIG. 3A is a schematic graph showing the effect on the substrate of implementing one embodiment of the present invention. As shown in FIG. 3A, portions of the substrate are maintained at different temperatures in different sections. The graph of FIG. 3A schematically represents the temperature of a plurality of points on the surface of the substrate being subjected to annealing. These points are arranged on a line drawn through the processing section. The first section 302 can be maintained at a high temperature selected to anneal the substrate surface. This section may correspond to anneal region 104 of FIG. 1A, anneal region 204 of FIG. 2, or any region of the substrate that is to be heated to a high temperature.

  The embodiment of FIG. 3A is characterized in that the second section 304 is typically maintained at a different temperature. This temperature is lower in the example of FIG. 3A. In some embodiments, the second section 304 can surround the first section 302. In other embodiments, the second section 304 can be adjacent to the first section 302, can overlap the first section 302, or can be spaced from the first section 302. . The temperature in the second zone 304 is typically lower than the temperature in the first zone 302. The temperature of the second zone 304 can be selected to preheat portions of the substrate, thereby reducing thermal stress on the substrate due to very rapid temperature changes.

  Typically, a third section 306 is also defined on the substrate. In most embodiments, the third zone 306 is the zone where ambient temperature prevails. Accordingly, in many embodiments, the third section 306 can be a surrounding section. However, in some embodiments, the third section 306 can also receive thermal energy applied, for example, by ambient heating by a heated support, or by further use of electromagnetic energy. According to the concept of progressively preheating as it approaches the first section 302, the temperature of the third section 306 is typically lower than the temperature of the second section 304. The third section 306 can surround the second section 304 in some embodiments, or can be adjacent to the second section in other embodiments. In some embodiments, the temperature in the third zone is maintained at less than about 500 degrees Celsius.

  The second section 304 can have a temperature between the temperature of the first section 302 and the temperature of the third section 306. In order to achieve the desired preheating, the temperature in the second zone 304 is about 30% to about 70% of the total temperature rise from the temperature in the third zone 306 to the temperature in the first zone 302. Can bring. In some embodiments, the temperature increase in the second section 304 relative to the third section 306 is about 50% of the temperature increase in the first section 302 relative to the third section 306.

  In some embodiments, the temperature of the first section 302 can be about 1,100 ° C. to about 1,400 ° C., such as about 1,250 ° C. to about 1,350 ° C. In some embodiments, the temperature difference between the first interval 302 and ambient temperature is between about 90% and about 99%, such as about 95% of the temperature difference between the melting point of the substrate and ambient temperature. In some embodiments, the temperature of the second section 304 can be between about 300 degrees Celsius and about 800 degrees Celsius. The temperature of the second section 304 is typically selected to reduce thermal stress at the boundary between the first section 302 and the second section 304, but also typically a portion of the substrate is amorphized. Below level. The temperature of the second zone 304 is typically selected to cool the annealed portion while preheating the portion of the substrate to be annealed. The temperature in the second section 304 is typically lower than that required to remove atoms from the crystal lattice. In one exemplary embodiment featuring a silicon-containing substrate, the temperature of the first section 302 is about 1,350 ° C., the temperature of the second section 304 is about 650 ° C., and a third The temperature in section 306 can be about 20 ° C. or another ambient temperature.

  3B and 3C are schematic views of the substrates, with a plurality of processing sections defined on each substrate. These processing sections represent areas of the substrate that are heated by electromagnetic radiation. In the embodiment of FIG. 3B, the first section 302B is surrounded by the second section 304B and the third section 306B. Note that these sections can have similar or different shapes. The embodiment of FIG. 3B is characterized in that the first section 302B is square and the second section 304B and the third section 306B are circular. In an alternative embodiment, all three sections can have a circular shape. In the embodiment of FIG. 3C, the first section 302C is a square, the second section 304C adjacent on one side to the first section 302C is a square or a square, all of which are the surrounding sections. It is characterized by being surrounded by a section 306C. Note also that the second section can be maintained at a single temperature throughout, or portions of the second section can be maintained at different temperatures. For example, the second section 304B of the embodiment of FIG. 3B can be a single temperature throughout, and the second section 304C of the embodiment of FIG. 3C can have portions of different temperatures. When a part of the second section 304C is a preheating section and another part is a cooling section, the preheating section can be maintained at a higher temperature than the cooling section. Note that any reasonable shaped substrate, such as circular, square, or any other planar shape, would benefit from the embodiments of the invention described herein.

  In some embodiments, there may be multiple hot zones between the ambient zone and the anneal zone. Some embodiments may be characterized in that there are multiple preheat sections for a single anneal section. Some embodiments may feature a first plurality of preheating sections and a second plurality of cooling sections. In some embodiments, one section can surround the next higher temperature section, so that each section surrounds another section and is surrounded by another section. In such an embodiment, the shape may have concentric circles, or sections close to nested circles (ie, non-concentric circles) located at different points in the center. In some embodiments, many differently shaped sections may be useful, such as a variety of different polygonal shapes, such as triangles, squares, squares, trapezoids, hexagons, and the like. Of course, different shapes can be used for different sections. In other embodiments, a section can be adjacent to the next higher temperature section on one side and the next lower temperature section on the other side. In still other embodiments, some sections can be adjacent to other sections, and some sections can surround other sections. For example, the first section can be defined as the annealing section, and among the adjacent second sections, the first side of the first section is for preheating, and the second section of the first section is the second section. The side is for cooling. Both the first section and the second section are surrounded by the third section, the third section is maintained at a temperature above the ambient temperature, and all other sections maintained at the ambient temperature are the fourth section. Surrounds.

  In one exemplary embodiment, the square anneal zone may be surrounded by one or more preheat zones shaped like a rectangle with the opposite side being a triangle. Such a tapered shape can facilitate heating and cooling of the substrate surface in a desired manner. In another exemplary embodiment, the annealing section, which can be square or circular, can be surrounded by one or more preheating sections having a teardrop shape. The round part of the teardrop shape can be used as the preheating section, and the “tail” of the teardrop can be used as the cooling section.

  In some embodiments, one or more of the preheating or cooling sections can be spaced from the annealing section, with a gap between the annealing section and the preheating and / or cooling section. For example, four sections can be defined on the substrate surface to be annealed: a peripheral section, a preheating section, an annealing section, and a cooling section. The annealing section can be a rectangle having two long sides of 11 mm and two short sides of 100 μm. The preheating section can be an isosceles triangle with a base of 13 mm and a height of 5 mm. This base is parallel to the long side of the annealing section, is spaced about 1 mm from the long side of the annealing section and is centered with respect to the annealing section, and thus a line that bisects the isosceles triangle However, the annealing section is also equally divided into two rectangles having a length of 5.5 mm and a width of 100 μm. The cooling zone can also be an isosceles triangle similar to the preheating zone. When the temperature of the annealing zone is 1,200 ° C., the temperature of the preheating zone can be about 600 ° C. to about 700 ° C. Therefore, the temperature of the substrate surface can be set so that the substrate has a gap between the heating zone and the annealing zone. Slightly decreases as it passes. For example, the temperature of the substrate surface decreases to about 500 ° C. before proceeding into the annealing zone. Such a preheating profile would be useful to minimize atomic perturbations deep in the bulk of the substrate during surface preheating. By extending the length of the base of the isosceles triangle that forms the preheating section, it is possible to provide heating to the region of the substrate surface adjacent to the short side of the annealing section and prevent thermal stress that causes damage on the substrate. . A similar cooling section located adjacent to the long side of the annealing section opposite the preheating section may be useful for accelerating cooling while avoiding damaging thermal stresses.

  Some embodiments may feature multiple annealing zones and multiple zones having different intermediate temperatures. Each anneal section can be maintained at the same temperature or at a different temperature, as required by individual embodiments. In this type of embodiment, the preheating section is between the annealing sections, in the annealing section, around the annealing section, adjacent to the annealing section, surrounding the annealing section, or spaced from the annealing section. Can be defined. For example, in one embodiment, the substrate may be processed by an apparatus that defines multiple processing sections within each portion, in four portions. Accordingly, in each portion, the annealing section can be surrounded by a preheating section and further by surrounding sections, which simultaneously translate across each section to process the substrate. In such embodiments, these sections can be formed and configured in any of the ways described elsewhere herein, and each section can be used to manage the overall heat quantity of the substrate. The position of the heated section within can be maintained at a pre-selected distance from the heated section within other parts.

  In some embodiments, the preheating section, or preheating and cooling section, can be shaped in a convenient manner. As shown in the embodiment of FIG. 3C, an embodiment has been described in which the preheating and cooling sections are square and are disposed on two sides of the annealing section. In other embodiments, the shape of the preheat and cool sections can be tapered away from the anneal section. In embodiments where the preheating and cooling sections do not surround the annealing section, the preheating and cooling sections generally have the same extent as at least one dimension of the annealing section. In some embodiments, the preheating and cooling sections can become narrower with distance from the annealing section. In some embodiments, the preheating and cooling sections can have a triangular, trapezoidal, parabolic, oval, elliptical, or irregular shape. In other embodiments, the preheating and cooling sections can have a rectangular shape coupled to a semicircle. These shapes can be mixed so that the preheating section has one shape and the cooling section has another shape. In embodiments where the preheating and cooling sections surround the annealing section to form a single intermediate temperature section, the single intermediate temperature section can be similarly shaped. In some embodiments, the intermediate temperature zone surrounding the anneal zone can have an oval, elliptical, or diamond shape. In other embodiments, the anneal zone can be surrounded by a square zone. In still other embodiments, the intermediate temperature section can have an irregular shape or a complex regular shape, such as a pair of abutting trapezoids.

  In one embodiment, the intermediate temperature zone can have a generally oval shape and can be irregularly positioned relative to the anneal zone. In such an embodiment, the center of mass of the anneal section is offset from the center of mass of the intermediate temperature section. Therefore, the plurality of line segments drawn from the start point on the edge of the intermediate temperature section to the end point on the edge of the annealing section have a length ranging from the maximum value to the minimum value. Each line segment is perpendicular to the edge of the intermediate temperature zone at the respective start point. Sufficient preheating to maintain more distance in the direction of the anneal path between the edge of the anneal zone and the edge of the intermediate temperature zone and thus prevent substrate damage as the anneal energy moves across the surface of the substrate Once energy is applied and after annealing is complete, it may be advantageous to apply sufficient energy to the cooling section to facilitate rapid cooling without damage. In such an embodiment, the graph of temperature versus time for a particular point on the substrate surface can have a half-drop shape.

FIG. 4 is a schematic side view of an apparatus 400 according to another embodiment of the invention. A first energy source 402 and a second energy source 404 are arranged to direct energy toward the first surface 406 and the second surface 408 of the substrate 410, respectively. The first energy source 402 induces energy toward the first section 412 of the substrate 410. The second energy source 404 induces energy toward the second section 414 of the substrate 410. In most embodiments, the first section 412 is smaller than the second section 414 and the boundary of the second section 414 extends beyond the boundary of the first section 412 on all sides. In most embodiments, the first energy source 402 induces electromagnetic energy toward the substrate 410 and the first section 412 with energy selected to heat the first section 412 to an annealing temperature. The second energy source 404 irradiates the second section 414 with energy selected to heat the second section 414 to an intermediate temperature. By heating the second section 414 to an intermediate temperature, the portion of the substrate to be annealed is preheated to avoid extreme thermal stress due to abrupt temperature changes at the edges of the first section 412. Work. In general, an energy source designed to anneal the substrate delivers a power density of at least 1 W / cm ² to the substrate surface, and an energy source designed to simply heat the substrate is at least 0.1 W / cm. is a ² to deliver less power density than the power density required for annealing.

  In one aspect, the anneal region matches the dimensions of individual dies (eg, 40 “dies” shown in FIG. 1A) or semiconductor devices (eg, memory chips) formed on the surface of the substrate. Dimensions are set. Referring again to FIG. 1A, in one aspect, the anneal region 104 boundaries are aligned and dimensioned to fit within “kerf” or “scribe” lines 114 that define the boundaries of each die. In one embodiment, alignment marks and other conventional techniques typically found on the surface of the substrate are used before performing the annealing process so that the anneal region 104 can be properly aligned to the die. Is aligned with the output of the energy source 102. By sequentially placing the anneal regions 104 so that they only overlap within naturally occurring unused spaces / boundaries between dies such as scribe or kerf lines 114, energy is transferred within the region where the device is formed on the substrate. The need for overlap is reduced, thus reducing variations in processing results between overlapping anneal regions. This technique tightly controls the overlap between adjacent scanned regions to ensure uniform annealing across the desired region of the substrate because the overlap is limited to unused space between the dies. There is an advantage over conventional processing that sweeps the laser energy across the surface of the substrate because the need is no longer a problem. Also, by limiting the overlap to unused space / boundaries between the dies, processing uniformity results can be achieved over conventional scan anneal-type methods that utilize adjacent overlapping regions across all regions of the substrate. Improve. Thus, any overlap of energy delivered between the sequentially disposed annealed regions 104 can be minimized, so that the amount of exposure to energy delivered from the energy source 102 to process critical regions of the substrate is reduced. The amount of machining fluctuation due to fluctuation is minimized.

Referring to FIG. 1A, in one example, each sequentially disposed annealed region 104 is a rectangular region with dimensions of about 22 mm × about 33 mm (eg, area 726 square millimeters (mm ² )). In one aspect, the area of each sequentially disposed anneal region 104 formed on the surface of the substrate is between about 4 mm ² (eg, 2 mm × 2 mm) to about 1000 mm ² (eg, 25 mm × 40 mm). The anneal region 104 can be surrounded by a circular preheat region 112 and can extend up to about 100 mm beyond the edge of the anneal region 104. In one embodiment, such as that shown in FIG. 1A, the preheat region 112 preferably extends about 50 mm or more beyond the edge of the anneal region 104. The extent to which the preheat region or intermediate temperature region exceeds the anneal region typically depends on the size of the substrate and the energy delivery resources available. In most embodiments, it is desirable to dimension the various intermediate temperature regions so that power requirements are minimized while providing the heat management required for the embodiments. In some embodiments, the intermediate temperature region extends less than 100 mm, such as less than 50 mm, for example about 30 mm, beyond the anneal region in at least one direction.

  Referring now to FIG. 2, in another example, each anneal portion 208 can have dimensions similar to those of the anneal region 104 of FIG. 1A. The preheat region 210 is shown on both sides adjacent to the annealed portion 208 and is coextensive in one dimension of the annealed portion 208. In some embodiments, the preheat region 210 can extend from about 50 mm to about 100 mm beyond the edge of the annealed portion 208.

  The dimensions of the preheating section or region are usually selected to allow sufficient preheating within the preheating section. In some embodiments, each preheating section can be larger than the annealing section to allow sufficient preheating. In one embodiment characterized by sequentially exposing successive anneal regions, the time required to preheat the preheat zone to the desired temperature can be longer than the time required to anneal the anneal zone. . Accordingly, each position on the substrate can be subjected to two or more preheating processes.

  In most embodiments, the energy source is typically adapted to deliver electromagnetic energy to anneal a particular desired region of the substrate surface. Typical electromagnetic energy sources include, but are not limited to, optical radiation sources (eg, lasers), electron beam sources, ion beam sources, microwave energy sources, visible light sources, and infrared light sources. . In one aspect, the substrate can be exposed to pulses of energy from a laser that emits radiation at one or more suitable wavelengths for a desired period of time. In another aspect, a flash lamp can be used to generate visible light energy for pulsing onto the substrate. In one aspect, a pulse of energy from an energy source optimizes the amount of energy delivered to the anneal region and / or the amount of energy delivered over the duration of the pulse to perform a targeted anneal of the desired region. Adjusted as follows. In one aspect, the wavelength of the laser is tuned so that most of the radiation is absorbed by a silicon layer disposed on the substrate. In laser annealing processes performed on silicon-containing substrates, the wavelength of radiation is typically less than about 800 nm and can be delivered in the far ultraviolet (UV), infrared (IR), or other desired wavelengths. . In one embodiment, the energy source can be a high intensity light source such as a laser adapted to deliver radiation at a wavelength of about 500 nm to about 11 micrometers. In most embodiments, the annealing process is typically performed on a given area of the substrate for a relatively short time, such as on the order of about 1 second or less.

  In some embodiments, the energy source includes a plurality of radiators, at least one of the radiators emits the annealing energy described above, and at least one of the radiators emits preheat energy. The preheat energy can be continuous wave energy or can be delivered in pulses. The preheating energy can be coherent or non-coherent, monochromatic or polychromatic, polarized or non-polarized, or any combination or degree thereof. The preheat energy can be delivered as high intensity white light, as infrared light, or as laser light. High intensity white light can be delivered using a xenon lamp. Infrared light can be delivered using a heat lamp. In some embodiments, the preheat energy can be delivered as continuous wave radiation, with annealing energy delivered in pulses. The preheating energy is usually selected to raise the temperature of the substrate by a fraction of the amount required for annealing or melting. In one embodiment, a laser is placed over the work surface and the laser is surrounded by four heat lamps to preheat the area around the anneal zone. In another embodiment, four xenon lamps can be used instead of heat lamps to deliver high intensity white light.

  FIG. 5 is a schematic cross-sectional view illustrating a processing chamber 500 useful for practicing embodiments of the present invention. The processing chamber 500 includes an optically transparent window 506 formed on the chamber body 504. The chamber body 504 defines a processing volume 502. In one embodiment, the processing volume 502 can have an inert environment maintained by an inert gas source 512 and a vacuum pump 510 connected to the processing volume 502.

  A substrate support 508 is disposed in the processing volume 502. The substrate support 508 is configured to support and move the substrate 514 disposed on the upper surface 516. An energy source 518 is positioned outside the chamber body 504 and is configured to project energy through an optically transparent window 506. This energy source can be configured to project the anneal energy 520 and preheat energy 522 in any of the ways described elsewhere herein. The substrate support 508 can be connected to a temperature control unit 524 having cooling and heating capabilities for the substrate 514 disposed on the substrate support 508. The substrate support 508 can be connected to one or more precision stages 526 that allow for precise alignment and relative movement between the substrate 514 and the energy source 518 during processing.

  In one embodiment, a light sensor 528 can be used to help align the substrate 514 and the energy source 518. The optical sensor 528 can be positioned near the optically transparent window 506 and can be connected to the control unit 530. The control unit 530 is further connected to the high precision stage 526. During alignment, the optical sensor 528 can be “observed” from the optically transparent window 506 to locate visual markers on the substrate 514, such as notches, and scribe lines around the die. The control unit 530 processes the signal from the optical sensor 528 to generate a control signal to the high precision stage 526 for alignment adjustment.

  As noted above, due to power requirements, the substrate is typically annealed only a portion at a time. After each individual anneal, the electromagnetic energy must be translated relative to the substrate to illuminate the next anneal portion. FIG. 6 is a schematic top view of a substrate 600 including 40 square dies 602 arranged in an array. Each die 602 is delimited by a scribe line 604. Scribe line 604 also defines an unused area 606 between the dies. In order to project a first quantity of energy toward a single die 602, a first energy projection region 608 is provided. In general, the first energy projection area 608 is greater than or equal to the area of each die 602, but can cover an area that is smaller than the sum of the area of each die 602 plus the unused area 606 surrounding the scribe line 604, Thus, the energy delivered within energy projection region 608 completely covers die 602 but does not overlap with adjacent die 602. A second energy projection region 610 is provided to surround the first energy projection region 608 and deliver a second quantity of energy to the substrate 600. The first quantity of energy is typically different from the second quantity of energy. In some embodiments, the first quantity of energy has a higher intensity and greater power than the second quantity of energy. In some embodiments, the first quantity of energy can be selected to anneal a portion of the substrate surface within the first energy projection region 608. In other embodiments, the first quantity of energy can be selected to preferentially melt a portion of the substrate surface within the first energy projection region 608. The second quantity of energy can be selected to preheat a portion of the substrate surface within the second energy projection region 610. The increase in preheat temperature of the second energy projection region 610 may be a fraction of the temperature reached in the first energy projection region 608, such as about 30% to about 70%, preferably about 50%. it can. Thus, the second energy projection region 610 maintains the temperature of the substrate surface in that region below the temperature reached in the first energy projection region 608, and thus between the first and second energy projection regions. The thermal stress generated in the substrate by the interface temperature gradient is less than that required to damage the substrate.

  In order to perform the annealing process on a plurality of dies 602 extending across the entire substrate surface, the output of the substrate and / or energy source is positioned and aligned with respect to each die 602. In one embodiment, the curve 612 shows the relative movement between the die 602 of the substrate 600 and the energy projection regions 608 and 610 during the annealing sequence performed on each die 602 on the surface of the substrate 600. In one embodiment, this relative movement can be achieved by translating the substrate in the x and y directions to follow the curve 612. In another embodiment, this relative movement can be achieved by moving energy projection areas 608 and 610 relative to stationary substrate 600. The energy projection areas 608 and 610 can be moved by moving the energy source relative to the substrate 600 or by manipulating the energy itself. In one embodiment using electromagnetic energy, the energy can be manipulated using optics without moving either the substrate or the energy source. For example, one or more mirrors or lenses can direct the projected energy toward a continuous die 602 and move the energy projection areas 608 and 610 accordingly.

  In addition, a different path than that represented by curve 612 can be used to optimize throughput and processing quality depending on the particular arrangement of dies 602. For example, the alternate anneal path can follow a substantially spiral pattern, starting with a die 602 near the center of the substrate 600 and progressing in an expanding circular pattern, or a die 602 on one edge of the substrate. Start with a circular pattern that shrinks. In one embodiment, it may be advantageous to pursue an annealing path along a diagonal and proceed along a path drawn through the diagonal of die 602. Such a path can minimize the possibility of overlapping anneal regions on successive dies 602.

  As the energy source travels along the annealing path, the energy projection region moves along the surface of the substrate. The second energy projection area 610 in FIG. 6 precedes the first energy projection area 608 in all directions. Accordingly, the second energy projection region 610 can be used to preheat the portion of the substrate that is to be annealed within the first energy projection region 608. Preheating reduces the impact of thermal stress on the substrate and prevents damage to the substrate at the edge of the anneal region.

  In an alternative embodiment, the second energy projection area can be adjacent to the first energy projection area. For example, the second energy projection region can extend outward in the direction of the annealing path on both sides of the first energy projection region. Accordingly, the portion of the second energy projection region that advances in front of the first energy projection region as the projected energy proceeds along the annealing path can preheat the portion of the substrate that is to be annealed, The other part moderates the cooling of the substrate behind the anneal region. An apparatus adapted to perform this type of annealing process rotates the energy source when the tip of the substrate is reached, so that the energy source travels in a different direction and the second energy projection region continues to the first It would be advantageous to have a property that allows the energy projection area to be preceded.

  In one embodiment, during the annealing process, the substrate 600 moves relative to the energy projection areas 608 and 610 as shown by curve 612 in FIG. Once a particular die 602 is positioned and aligned within the first energy projection region 608, the energy source projects a pulse of energy toward the substrate 600, so that the die 602 is subject to a particular annealing process recipe. You are exposed to a specific amount of energy for a specified duration. The duration of the pulse energy typically results in relative motion between the substrate 600 and the first energy projection region 608 not causing any “blur” or non-uniform energy distribution across each die 602, resulting in substrate damage. Short enough to not bring. Thus, the energy projection areas 608 and 610 can move continuously with respect to the substrate 600, and a short burst of annealing energy strikes the various dies 602 in the first energy projection area. Similarly, the energy colliding with the second energy projection region 610 may be pulsed or continuous. If pulsed, the energy projected towards the second energy projection region is typically a temperature rise applied to the first energy projection region over the exposure time of the first energy projection region to manage the amount of heat of the substrate. Of about 30% to about 70%, more preferably about 50%, of a property selected to raise the temperature of the substrate surface in the second energy projection region at a significant rate.

  For example, if the first energy projection region receives a first pulse of incident energy that increases the temperature of the substrate from 20 ° C. to 1,300 ° C., such as a 10 nanosecond laser burst, to the second energy projection region. The second pulse of incident energy delivered should raise the temperature of the substrate in that region to at least about 600 ° C. during the first burst. If necessary, the second pulse can be made larger than the first pulse and heated in the second energy projection region time. In some embodiments, the second energy projection region includes the first energy projection region, an interval that begins before the first pulse and ends after the first pulse, and thus includes the first pulse. It may be advantageous for the second pulse delivered across to preheat the area subjected to the first pulse along with the adjacent area of the substrate.

  In other embodiments, the energy delivered to the first energy projection region is pulsed, whereas the energy delivered to the second energy projection region can be continuous. In some embodiments, multiple pulses of energy can be delivered to the first energy projection region while continuous energy is delivered to the second energy projection region.

  FIG. 7 is a schematic cross-sectional view of an apparatus 700 according to another embodiment of the present invention. The apparatus 700 includes a chamber 702 for processing the substrate 704. The substrate is positioned on a substrate support 706 inside the chamber 702. In the embodiment of FIG. 7, the substrate support 706 is represented as a ring to irradiate the substrate 704 from the front and back surfaces. In an alternative embodiment, the substrate 704 can be irradiated from only one side, and the substrate 704 can be located on a substrate support, such as the exemplary substrate support 508 of FIG. Lift pins 756, together with actuators 758, raise and lower the substrate support 706 to insert and remove the substrate from the chamber 702. Chamber 702 has a lower portion 708 and an upper portion 710 that together define a processing volume 712. The upper portion typically has an upper wall 726 that defines an upper working volume 712A on the substrate 704. The upper portion 710 may have an opening 714 for placing and retrieving a substrate and a gas inlet 716 for providing process gas from a process gas source 718. The upper portion 710 supports a first window 720 made from a material selected for light transmission and absorption properties. A first energy source 722 is positioned outside the chamber 702 and directs the first energy 724 towards the first window 720. The first window preferably passes some or all of the first energy 724 into the chamber 702.

  The lower portion 708 of the chamber 702 includes a lower chamber wall 728 that defines a lower processing volume 712B. The lower portion 708 can have a gas outlet 730 coupled to a pump 732 for removing process gas from the chamber 702. The lower portion 708 of the chamber 702 houses the second energy source 734. The second energy source 734 includes a plurality of light sources 736 for generating the second energy 738 and directing the second energy 738 toward the substrate 704. The second window 740 covers the plurality of light sources 736. Each light source is housed within a tube 746 that can be reflective to direct energy from the light source 736 towards the substrate 704. The light source 736 is typically powered by a power source 742. In the embodiment of FIG. 7, power from power source 742 is routed to switching box 744, which switches power from power source 742 to one or more of light sources 736. By controlling the operation of the switching box 744, the light source 736 can be selectively energized.

  In many embodiments, the light source 736 can be an infrared light generator, such as a heat lamp, but the light source 736 can also be a broad spectrum light, ultraviolet light, or wavelength across the broad spectrum from ultraviolet to infrared. It can also be configured to generate a combination of In some embodiments, the light source 736 can be a white light lamp, such as a halogen lamp, or a flash lamp. The second energy 738 generated by the light source 736 heats a portion of the substrate 704 to a temperature that is not high enough to anneal the substrate. Accordingly, the light source 736 serves as a preheating energy source. Accordingly, the portion of the substrate 704 that is processed by the second energy 738 is the preheating section 746.

  In many embodiments, the first energy source 722 can be a laser capable of generating light of a wavelength that is easily absorbed by the substrate 704. In other embodiments, the first energy source 722 can be a flash lamp or a white light source. The first energy 724 generated by the first energy source 722 heats that portion of the substrate 704 to a temperature high enough to anneal the portion of the substrate 704. Accordingly, the first energy source 722 serves as an annealing energy source. Accordingly, the portion of the substrate 704 that is processed by the first energy 724 is the anneal zone 748.

  As described above, the substrate 704 is preferably processed part by part. An actuator 750 is provided to position the first energy source 722 over the anneal region 748. The controller 752 operates the actuator 750 to position the first energy source 722 above the annealing section 748 and operates the switching box 744 to direct the preheating energy toward the preheating section 746. The power is switched to one or more light sources 736. In this way, a portion of the substrate is preheated before annealing. The controller 752 operates to move both the preheat section 746 and the anneal section 748 so that any portion of the substrate 704 that is annealed is first preheated, but the majority of the substrate 704 that defines the peripheral section 754. Remains at ambient temperature.

  8A and 8B are graphs showing temperature-time profiles for two embodiments of the present invention. Each graph shows the temperature at one point on the surface of the substrate being subjected to thermal processing according to an embodiment of the present invention. As described above, the substrate moves relative to an energy source that directs energy toward the substrate surface. In FIG. 8A, when an exemplary point on the substrate surface moves from the ambient section to the first preheat section, the temperature at that point is changed from the ambient temperature in the ambient temperature interval 800 to the first in the first preheat interval 802. Move to the preheating temperature. As described elsewhere herein, the first preheat temperature is typically lower than the temperature required to anneal the substrate surface. As the exemplary point moves from the first preheating interval to the second preheating interval, the temperature at that point is changed from the first preheating temperature in the first preheating interval 802 to the second in the second preheating interval 804. Move to the preheating temperature. The embodiment of FIG. 8A shows four sections defined on the substrate surface: a peripheral section, two preheat sections, and an anneal section. As an exemplary point on the substrate surface moves from the second preheat interval to the anneal interval, the temperature at that point moves from the second preheat temperature within the second preheat interval 804 to the anneal temperature within the anneal interval 806. . An exemplary point is that when moving from the annealing interval to the lower temperature interval again, the first preheating interval 802 in the second cooling interval 810 up to the condition of the second preheating interval 804 in the first cooling interval 808. And finally to ambient conditions within the second ambient interval 812. Note that alternative embodiments may be characterized in that the temperature during the cooling intervals 808 and 810 is different from the temperature within the preheating intervals 802 and 804. Accordingly, the temperature within the cooling interval 808 may be higher or lower than the temperature within the preheating interval 802, and the temperature within the cooling interval 810 may be higher or lower than the temperature within the preheating interval 804. It should be understood that similar embodiments may feature only one preheat interval or more than two preheat intervals. Similarly, some embodiments may feature only one cooling interval or more than two cooling intervals.

  The graph of FIG. 8B illustrates the temperature-time profile of one point on the substrate surface that has been subjected to thermal processing according to another embodiment of the present invention. In the embodiment of FIG. 8B, similar to the embodiment of FIG. 8A, the exemplary points on the substrate surface move from the peripheral spacing 850 to the first preheating spacing 852. The exemplary point then moves into the second preheat interval 854. The second preheat interval 854 is characterized by a varying temperature-time profile. In this embodiment, as the exemplary point moves through the second preheat interval 854, the temperature at that point increases from the first preheat temperature to the second preheat temperature. This increase can be linear as shown in interval 854, or can have some other profile, and even within the generally rising temperature-time profile of the second preheat interval 854. Short intervals where the temperature decreases can also be included. An exemplary point moves into the anneal interval 856 and then into the first cooling interval 858. The first cooling interval 858 can also have a varying temperature-time profile that is similar to that of the second preheating interval 854. The exemplary point then moves into the second cooling interval 860 followed by the second peripheral interval 862.

  FIG. 9 is a flow diagram illustrating a method 900 according to one embodiment of the invention. At 910, a substrate is provided in the heat treatment chamber. At 920, a plurality of sections are defined on the surface of the substrate. Each section is processed using electromagnetic energy with a different power level. In most embodiments, there are at least three sections, but embodiments of the invention are contemplated to feature two sections or more than four sections. In most embodiments, at least one section is an anneal section and is treated with electromagnetic energy selected to anneal the surface of the substrate. In some embodiments, it may be desirable to melt the substrate surface within at least one anneal zone. In most embodiments, at least one section is a preheat section. In some embodiments, one or more sections can be sections that combine preheating and cooling, while in other embodiments, one or more sections are exclusively preheating or cooling sections. It can be.

  In one aspect, a substrate is disposed on the substrate support and a first quantity of electromagnetic energy is induced toward the first portion of the substrate. In addition, a second quantity of electromagnetic energy is induced towards the second portion of the substrate. The first portion of the substrate surrounds the second portion of the substrate, the first quantity of electromagnetic energy preheats the first portion of the substrate, and the second quantity of electromagnetic energy is applied to the second portion of the substrate. Anneal. The first quantity and the second quantity are moved across the substrate to maintain a constant spatial relationship between the two quantities of energy, and thus the regions in the first and second portions of the substrate as the energy moves. Moves.

In another aspect, the electromagnetic energy delivered in the two quantities can be of any desired nature. Each quantity of energy can be coherent or incoherent, monochromatic or polychromatic, polarized or non-polarized, and continuous or pulsed to any degree. Each quantity of energy can be delivered by one or more lasers, high intensity white light lamps, flash lamps, heat lamps, or combinations thereof. The two quantities of energy can be delivered by electromagnetic energy that differs only in intensity, or the two quantities may differ by any desired degree in any of the above characteristics. In one example, the first quantity can be delivered by one or more lasers, each laser delivering at least 100 W / cm ² of power at a wavelength of less than about 850 nm. These lasers can be pulsed or continuous wave energy sources. In pulsed embodiments, pulsing can be achieved by circulating power to the laser or by optical switching that intermittently prevents the laser light from leaving the optical assembly. In another example, the second quantity, be delivered by about 25W / cm ^2, such as one or more lamps delivering incoherent light at 50 W / cm ² less than the power level to the second portion Can do.

  FIG. 10 is a flow diagram summarizing a method 1000 according to another embodiment of the invention. At 1010, a substrate is positioned on a substrate support in a thermal processing chamber. At 1020, a first source of electromagnetic energy is directed toward a first portion of the substrate. At 1030, a second source of electromagnetic energy is simultaneously directed toward the second portion of the substrate. As described elsewhere herein, one of these sources can be configured to deliver annealing energy and the other source is configured to deliver preheating energy. At 1040, the substrate is translated relative to the first and second energy sources. By translating the substrate, the energy delivered is translated across the entire surface of the substrate, annealing the entire surface in portions. In the embodiment of FIG. 10, these energy sources are substantially stationary as the substrate moves, but certain embodiments are characterized in that the energy source or energy moves in addition to the substrate moving. can do. The translation of the substrate is typically accomplished by using a movable substrate support such as a high precision stage that can position the substrate at a precise location within the apparatus.

  In most embodiments, these sections are maintained at different temperatures. In some embodiments, these sections are heated by inducing various types and strengths of electromagnetic energy toward the substrate surface. In the embodiment of FIG. 9, at 930, each section is illuminated using different power levels of electromagnetic energy. In other embodiments, additional heat can be applied to the substrate by using a heated substrate support that contacts the backside of the substrate. In still other embodiments, portions of the substrate can be selectively cooled by a cooled substrate support that contacts the backside of the substrate. The temperature within at least one of these sections is selected to anneal the surface of the substrate. The temperature in at least one of these sections is selected to preheat the surface of the substrate and is lower than the temperature required to anneal the substrate surface. One leg receives the maximum power level. This section can be an annealing section. The other leg receives a lower power level. One or more intervals may receive a high power level below the maximum power level. These sections can be preheated sections. Still other sections can receive negligible power or can be cooled. Some sections can be ambient sections and the substrate temperature is maintained at ambient temperature.

  In some embodiments, the different sections can be illuminated using different electromagnetic energy sources. One or more lasers can provide electromagnetic energy. The first laser can generate energy for annealing a portion of the substrate in one section, and the second laser can generate energy for preheating a portion of the substrate in another section. can do. In an alternative embodiment, multiple lasers can preheat portions of the substrate. In another embodiment, such as the embodiment of FIG. 7, one or more heat lamps can preheat portions of the substrate.

  In embodiments where the plurality of sections include annealing sections, sections that provide a preheating or cooling function can be shaped to facilitate preheating or cooling. In an exemplary embodiment where the annealing section has a preheating section on one side and a cooling section on the opposite side, the preheating section and the cooling section can have a tapered shape, and the first edge is the annealing section. A second edge that is in contact with the edge of the substrate and is coextensive with the edge of the anneal zone and shorter than the first edge opposite the first edge forms a trapezoidal shape. . In an alternative embodiment, the preheating and cooling sections can be triangular shaped, each one edge having the same extent as the edge of the annealing section. In other alternative embodiments, the tapered tip of the preheating and cooling section can be curved, and in some embodiments can be parabolic or semi-circular.

  Multiple sections with different temperatures and shapes are typically subject to electromagnetic energy designed to excite atomic motion within the substrate lattice while maintaining thermal stress below a threshold level that would otherwise damage the substrate. Exposing a portion of the substrate surface allows rapid annealing of the substrate. The preheating and cooling section allows the annealing process to begin at a high temperature to speed up the final temperature ramp up and cooling during annealing. The tapered shape of the preheat and cool sections can serve to minimize thermal exposure of the unannealed portion of the substrate, thereby allowing atoms that may have been moved to another position by the annealing process, Or, minimize the undesirable movement of atoms that may have been in the desired location prior to annealing. In general, the number and shape of the preheating and cooling sections can be selected to facilitate the desired annealing process.

  The above embodiments are usually characterized in that the plurality of sections have a substantially constant temperature. The first interval is maintained at the first temperature, the second interval is maintained at the second temperature, and so on. In other embodiments, the one or more sections can have a temperature gradient to facilitate heating or cooling near the annealing section. For example, in a three-section embodiment, the first section, which can be a preheating section, can have a temperature gradient that increases toward a second section, which can be an annealing section. Similarly, the third section, which can be a cooling section, can have a temperature gradient that increases towards the second section. The temperature gradient provides the same general function as the tapered section shape described above. A temperature gradient can be established within a given interval by adjusting the delivered energy using an optical system to achieve a desired temperature profile.

  In one exemplary embodiment, a single energy source with sufficient power to anneal the substrate can be oriented to induce electromagnetic energy toward the substrate. A lens having a defocus characteristic can be disposed between the energy source and the substrate. The lens may have a first portion that defocuses a corresponding first portion of electromagnetic energy and a second portion that further focuses or leaves the second portion of electromagnetic energy unchanged. it can. For example, when a laser is used as the electromagnetic energy source and a circular annealing energy beam having a diameter of 2 mm is formed using the shaping optical system, a circular central portion having a radius of 0.5 mm is formed between the shaping optical system and the substrate. A lens surrounded by a concentric annular outer part with a radius of 1.5 mm can be arranged. The circular central portion can have neutral optics, if desired, or can focus a portion of the annealing energy beam incident on that portion. The concentric annular outer portion of the lens can be shaped to reduce the strength of the outer portion of the anneal energy beam. The reduced intensity energy then strikes the surface of the substrate with sufficient power to preheat without annealing the preheated portion of the surface, and the unaltered or focused portion anneals the annealed portion within the preheated portion. To do.

  FIG. 11 is a flow diagram summarizing a method 1100 according to another embodiment of the invention. At 1102, a substrate is positioned on a substrate support in a thermal processing chamber. At 1104, a plurality of sections are defined on the substrate surface. At 1106, the first portion of these sections is maintained at ambient temperature. The ambient temperature can be room temperature in some embodiments, or can be elevated in other embodiments. In most embodiments, the ambient temperature is below about 200 ° C., but some embodiments may be characterized by the ambient temperature as high as 350 ° C. Ambient temperature can be maintained by using a heated substrate support or by irradiating the substrate with electromagnetic energy suitable for the desired heating.

  At 1108, preheating energy is provided to a second portion of the defined sections to heat these sections to one or more intermediate temperatures above ambient temperature. Each section can be heated to the same intermediate temperature or to a different intermediate temperature. The interval closer to the region to be annealed is usually maintained at a temperature above the temperature of the region further away from the region to be annealed. In embodiments where the second portion includes more than one section, the intermediate temperature can be stepped up from the ambient temperature to the annealing temperature. The temperature difference between the intermediate temperature and the ambient temperature is typically about 10% to about 90%, such as about 30% to about 70%, such as about 50%, of the temperature difference between the annealing temperature and the ambient temperature. In an exemplary embodiment where the second portion includes two sections, the temperature difference between the first intermediate temperature section and the ambient section can be about 40% of the temperature difference between the anneal temperature and the ambient temperature, The difference between the intermediate temperature interval and the ambient interval is about 60% of the difference between the annealing temperature and the ambient temperature.

  At 1110, annealing energy is provided to a third portion of the defined intervals to cause the intervals to be higher than ambient and intermediate temperatures to one or more annealing temperatures selected to anneal the substrate surface. Heat. These annealing sections, including the third portion of the defined section, can have any of the spatial relationships described herein. In addition, different annealing temperatures can be applied to different annealing sections if desired.

  At 1112, one or more of the above temperatures can be detected and used to control the delivery of preheat energy, anneal energy, or both to keep the thermal gradient between intervals below a threshold level. In some embodiments, one or more thermal imaging devices can be used to detect various intervals of temperature. The temperature of one section can be compared with the temperature of another section to determine if the thermal gradient between sections is excessive. The energy delivered to one or more of the detected intervals can be modulated based on the detected temperature to increase or decrease the thermal gradient between these two intervals. If the substrate is annealed by moving the energy source, the detector can be located at the same location as the energy source so as to follow the annealing and preheating section around the substrate. If the substrate is annealed by moving only the energy (eg, using a mirror), similar optics are used to focus the detector on the portion of the substrate being processed under the direction of the controller. Or the entire substrate can be sampled and the computer can be used to determine the thermal gradient.

In one exemplary embodiment, the substrate can be positioned on a support in a thermal processing apparatus. The substrate can be held in place on the support by any means known in the art, including electrostatic or vacuum means. A laser is positioned over the substrate and oriented to produce a light beam that impinges on the substrate in a direction substantially perpendicular to the plane of the substrate. This laser can be coupled to an optical assembly adapted to position the laser in three dimensions. The laser can be adapted to deliver up to 10 kW / cm ² of laser energy to an anneal region of a 22 mm × 33 mm substrate. The laser is preferably tuned to a wavelength that is easily absorbed by the substrate, such as less than 800 nm for a silicon substrate.

  In operation, the laser can be switched using an electrical switch coupled to a power source or an optical switch coupled to a laser or optical assembly. These switches can be configured to switch the laser on and off in less than 1 microsecond (μsec), so that the laser delivers a pulse of energy lasting from about 1 μsec to about 10 milliseconds (msec). Can do.

  In this example, the preheating light source is located at the same location as the laser in the optical assembly. This preheating light source can be another laser, a xenon lamp, or a heat lamp, so as to deliver up to 500 W of electromagnetic energy to a substantially circular region of about 2 cm in diameter that includes and is concentric with the annealing region. Can be adapted. The preheating light source can be focused using a suitable lens and mirror to capture and direct all of the energy of the preheating light source. The preheating light source can be located in a housing positioned proximate to the laser source, so that light from the preheating light source illuminates the area of the substrate that includes the area to be annealed. The preheating light source can be slightly tilted to center the preheating region around the anneal region. Alternatively, the preheating light source can project energy onto the substrate substantially perpendicular to the plane of the substrate and uses optics to spread the light across the preheating region, including the annealed region. The preheating light source may then advantageously be positioned with respect to the laser such that the preheating region extends further from the annealing region in the direction of the annealing path. The optical assembly can be further adapted to rotate so that the preheating light source maintains an advantageous position relative to the laser as the annealing path changes direction.

  The processing apparatus is preferably configured to translate the substrate relative to the optical assembly by using a movable stage of a type known in the art. In operation, this stage positions the substrate below the optical assembly so that the target area of the substrate is exposed to the optical assembly. The preheating light source can be lit continuously and illuminates the substrate with preheating energy when there is no annealing energy. The continuous preheating energy heats the surface of the substrate in the region including the anneal target region to at least 600 ° C. The laser emits one or more pulses to the target anneal region. These pulses can be short enough that the stage moves continuously along the annealing path without blurring the laser pulse. The preheat zone moves along the surface of the substrate as the stage moves and heats a portion of the substrate to the target preheat temperature as it approaches the target anneal zone. Thus, the portion of the substrate that is immediately adjacent to the target anneal region is not subjected to thermal stress that causes damage due to the high thermal gradient at the edge of the target anneal region.

  In an exemplary alternative embodiment, the laser can be surrounded by two to four preheat energy sources spaced around the laser in an optical assembly. By using multiple preheating sources, uniform preheating is possible over the entire preheating area of the substrate. Alternatively, the laser can involve two different preheat energy sources adapted to illuminate different areas of the substrate. One source of preheat energy can be adapted to illuminate a circular area, for example, about 3 cm in diameter, and another source of preheat energy can be a concentric circle, about 1.5 cm in diameter, that is also concentric with the annealed area. Illuminate the area. Accordingly, two preheating regions are formed. The two preheat sources can deliver a similar amount of energy, so a source that illuminates a larger area has a lower temperature rise than a more focused source. In one embodiment, a preheat source that illuminates a large area can heat the area to a temperature of 300 ° C. or higher, and a preheat source that illuminates a smaller area within the wide preheat area Can be heated to a temperature of 700 ° C. or higher. The anneal pulse can then anneal the substrate by delivering sufficient energy to raise the temperature of the anneal region to 1200 ° C. or higher without melting the substrate material.

  In another exemplary embodiment, a single energy source can be used. For example, the laser can be adapted to produce a single column of light that can be used for both preheating and annealing energy. Typically, optics are used, including mirrors, lenses, filters, and beam splitters, to tune the laser light to have the desired polarity or coherence. Such an optical system may also include a lens that blurs a portion of the laser light. Next, the portion where the focus of the laser beam is blurred can be guided to a region surrounding the annealing region. For example, a laser mounted in a suitable optical system can produce a cylindrical coherent light beam with a diameter of about 1 mm. The beam may be directed through a lens having a circular, non-refractive central portion having a diameter of about 0.8 mm and an outer portion that blurs an annular focus having an inner diameter of 0.8 mm and an outer diameter greater than 1 mm. it can. The part of the laser beam that passes through the non-refractive part of the lens continues to reach the substrate and anneals the exposed part of the substrate, whereas it passes through the part of the laser beam that defocuses the lens. The part that has been reduced in intensity spreads over a wider area and heats the area to a lower temperature.

  While the above is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.

Claims (15)

A method of processing a substrate, comprising:
Positioning the substrate on a movable substrate support;
Inducing a first quantity of heating energy toward a first fixed position below a portion of the substrate;
Inducing a second quantity of heating energy toward a second fixed position below a portion of the substrate;
Processing the selected region of the substrate by moving the substrate support and sequentially positioning each selected region over the first fixed position and then over the second fixed position; When,
Maintaining a portion of the substrate at a temperature below 500 degrees Celsius.   The method of claim 1, wherein the second quantity of heating energy has sufficient power to anneal a portion of the substrate.   The method of claim 2, wherein the first quantity of heating energy has a power that is less than a power required to anneal a portion of the substrate. A method of annealing a substrate surface,
Preheating the preheated portion of the substrate surface by applying energy to the preheated portion;
Annealing the annealed portion of the substrate within the preheated portion by applying incremental energy to the annealed portion while preheating the preheated portion of the substrate. An apparatus for heat-treating a substrate,
A movable substrate support;
A first energy source oriented to induce annealing energy toward a first portion of the surface of the substrate support;
A second energy source oriented to induce preheating energy toward a second portion of the surface of the substrate support;
And an optical assembly containing said first and second energy sources.   The apparatus of claim 5, wherein the first energy source is a laser and the second energy source is a laser.   The apparatus of claim 5, wherein the first energy source is a laser and the second energy source is a plurality of lamps.   The apparatus of claim 5, wherein the optical assembly further comprises a first optical tuner for shaping the annealing energy and a second optical tuner for shaping the preheating energy.   The apparatus of claim 5, further comprising a control device coupled to the substrate support. An apparatus for heat-treating a substrate,
A fixed substrate support;
One or more oriented to induce annealing energy toward a first portion of the surface of the substrate support and to induce preheating energy toward a second portion of the surface of the substrate support. Energy sources,
An optical assembly containing the one or more energy sources;
And an actuator for moving the annealing energy and the preheating energy relative to the fixed substrate support.   The apparatus of claim 10, wherein the at least one energy source is a laser.   The apparatus of claim 10, wherein the optical assembly further comprises one or more optical tuners for shaping the annealing energy and the preheating energy.   The apparatus of claim 10, further comprising a controller coupled to the actuator.   The apparatus of claim 10, further comprising a detector for sensing the temperature of one or more portions of the substrate.   The apparatus of claim 10, wherein the actuator rotates the optical assembly to direct the annealing energy and the preheating energy.

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