JP6546512B2 - Heat treatment equipment - Google Patents

Description

  The present invention relates to a heat treatment apparatus for heating a thin plate-like precision electronic substrate (hereinafter, simply referred to as a “substrate”) such as a semiconductor wafer by heating the substrate.

  In the semiconductor device manufacturing process, impurity introduction is an essential step for forming a pn junction in a semiconductor wafer. At present, impurity introduction is generally performed by ion implantation and subsequent annealing. The ion implantation method is a technology for physically implanting impurities by ionizing elements of impurities such as boron (B), arsenic (As), and phosphorus (P) and causing them to collide with a semiconductor wafer at a high acceleration voltage. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurities are deeply diffused by heat, and as a result, the junction depth becomes too deep than required, which may cause a problem in forming a good device.

  Therefore, flash lamp annealing (FLA) has recently attracted attention as an annealing technique for heating a semiconductor wafer in a very short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating flash light onto the surface of the semiconductor wafer using a xenon flash lamp (hereinafter simply referred to as a xenon flash lamp when it is referred to as “flash lamp”). It is a heat treatment technology that raises the temperature of only the surface for a very short time (a few milliseconds or less).

  The emission spectral distribution of the xenon flash lamp is in the ultraviolet region to the near infrared region, has a shorter wavelength than that of the conventional halogen lamp, and substantially matches the basic absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, it is possible to rapidly increase the temperature of the semiconductor wafer because the amount of transmitted light is small. It has also been found that only the vicinity of the surface of the semiconductor wafer can be selectively heated if the flash light irradiation is performed for an extremely short time of several milliseconds or less. For this reason, if the temperature rise for a very short time by a xenon flash lamp, only impurity activation can be performed without deeply diffusing the impurity.

  In a heat treatment apparatus using a flash lamp, the temperature of the peripheral portion of the semiconductor wafer tends to be relatively lower than that of the central portion. The cause of such nonuniform temperature distribution may be thermal radiation from the peripheral portion of the semiconductor wafer, or thermal conduction from the peripheral portion of the semiconductor wafer to the relatively low temperature quartz susceptor.

  On the other hand, with the miniaturization of semiconductor devices and the increase in diameter of semiconductor wafers, semiconductor manufacturing equipment is required to have even more severe process uniformity, and even in a flash lamp annealing equipment, uniformity of temperature distribution during heat treatment There is a strong demand for improvement. For example, Patent Document 1 discloses a quartz window provided between a flash lamp and a holder for holding a semiconductor wafer. It has been proposed to place an illumination control plate having a diameter smaller than the diameter of the semiconductor wafer on the top. While the light quantity of light reaching the inner part of the semiconductor wafer is reduced by the illuminance adjustment plate, the light quantity of light reaching the peripheral part of the semiconductor wafer is not reduced, so the temperature of the central part of the semiconductor wafer is relatively lowered. As a result, the uniformity of the in-plane temperature distribution of the semiconductor wafer is improved.

JP, 2006-278802, A

  By the way, conventionally, the flash lamp annealing apparatus has typically performed the heat treatment generally at normal pressure, but in recent years the flash lamp annealing is applied to other than activation of impurities (for example, heat treatment of high permittivity gate insulating film) There is a need to set the inside of the chamber of the flash lamp annealing apparatus to a reduced pressure atmosphere in combination with the attempts to be made. In order to make the inside of the chamber into a reduced pressure atmosphere, it is necessary to make the chamber structure into a pressure-resistant structure, and the thickness of the quartz window that transmits flash light from the flash lamp must be thicker than that of the conventional atmospheric pressure specification. You must.

  When an illuminance adjusting plate as disclosed in Patent Document 1 is placed on a thick quartz window, light incident on the quartz window from the side of the illuminance adjusting plate is subjected to multiple reflections on the upper and lower surfaces of the quartz window. A phenomenon occurs in which the area near the center of the semiconductor wafer located below the illuminance adjustment plate is repeatedly irradiated. Then, the illuminance adjusting plate prevents the light amount of light reaching near the central portion of the semiconductor wafer from being reduced, which causes a problem that the uniformity of the in-plane temperature distribution of the semiconductor wafer during the heat treatment is impaired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat treatment apparatus capable of improving the uniformity of the in-plane temperature distribution of the substrate regardless of the thickness of the quartz window.

In order to solve the above-mentioned problems, the invention according to claim 1 is a heat treatment apparatus for heating a substrate by irradiating the substrate with a chamber for housing the substrate, and provided in the chamber, the substrate being mounted. A supporting portion for supporting the light, a quartz window for closing the opening of the chamber, and a light irradiating portion provided outside the chamber and irradiating light to the substrate supported by the supporting portion through the quartz window A light reduction unit for reducing light emitted from the light irradiation unit to the inside of the chamber is provided on the opposite surface of the quartz window facing the support unit, and opposite to the opposite surface of the quartz window The surface further includes a circular light amount adjustment unit for adjusting the light amount of light incident on the quartz window from the light irradiation unit, and the light reduction unit has a circular shape smaller than the light amount adjustment unit. It features.

  The invention according to claim 2 is characterized in that the heat treatment apparatus according to the invention according to claim 1 further comprises an elevation part for raising and lowering the support part.

  The invention according to claim 3 is characterized in that, in the heat treatment apparatus according to the invention according to claim 1 or 2, the light reducing portion is provided at a central portion of the facing surface of the quartz window.

  The invention according to claim 4 is the heat treatment apparatus according to any one of claims 1 to 3, wherein the light reduction part is a rough surface having asperities formed on the opposing surface. I assume.

  The invention according to claim 5 is characterized in that, in the heat treatment apparatus according to the invention according to claim 4, the rough surface is formed in a part of a region where the light reduction portion is provided.

The invention according to claim 6 is characterized in that, in the heat treatment apparatus according to any one of the inventions according to any one of claims 1 to 5 , the light emitting unit includes a flash lamp for emitting flash light.

The invention of claim 7, in the heat treatment apparatus according to any one of claims 1 to invention of claim 6, wherein the light irradiation unit is characterized in that it comprises a halogen lamp.

According to the first to seventh aspects of the invention, the thick quartz window is provided on the opposite surface facing the support portion of the quartz window in order to provide a light reduction portion for reducing light emitted from the light irradiation portion into the chamber. It is also possible to reduce light incident upon repeated multiple reflections, and to improve the uniformity of the in-plane temperature distribution of the substrate regardless of the thickness of the quartz window. In addition, since the light quantity adjustment part for adjusting the light quantity of light incident on the quartz window from the light irradiation part is further provided on the surface opposite to the facing surface of the quartz window, the light from the light irradiation part is more effectively reduced. It can be lighted.

  In particular, according to the second aspect of the present invention, since the lifting and lowering unit for lifting and lowering the support unit is further provided, the degree of freedom in adjusting the light reduction range on the substrate by the light reduction unit is increased.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus which concerns on this invention. It is a top view of a chamber. It is sectional drawing of a susceptor. It is a top view of a delivery part. It is a top view showing arrangement of a plurality of halogen lamps. It is a figure which shows the light-reduction part and light quantity adjustment part which were provided in the upper side chamber window. It is the top view which looked at the upper side chamber window from the lower surface side. It is a figure which shows the other example of a light reduction part.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing the configuration of a heat treatment apparatus 1 according to the present invention. The heat treatment apparatus 1 of this embodiment is a flash lamp annealing apparatus which heats the semiconductor wafer W by irradiating the semiconductor wafer W having a disk shape with a flash light as a substrate. The size of the semiconductor wafer W to be processed is not particularly limited, and is, for example, φ300 mm or φ450 mm. A high dielectric constant film is formed on the semiconductor wafer W before being carried into the heat treatment apparatus 1, and post deposition annealing (PDA) of the high dielectric constant film is performed by heat treatment by the heat treatment apparatus 1. Ru. In order to clarify the directional relationship in FIG. 1 and the subsequent drawings, an XYZ orthogonal coordinate system in which the Z-axis direction is a vertical direction and the XY plane is a horizontal plane is appropriately attached. Further, in FIG. 1 and the subsequent drawings, the dimensions and the numbers of the respective parts are drawn in an exaggerated or simplified manner as necessary for easy understanding.

  The heat treatment apparatus 1 includes a chamber 6 for housing a semiconductor wafer W, a flash heating unit 5 containing a plurality of flash lamps FL, and a halogen heating unit 4 containing a plurality of halogen lamps HL. A flash heating unit 5 is provided on the upper side of the chamber 6 and a halogen heating unit 4 is provided on the lower side. The heat treatment apparatus 1 further includes a control unit 3 that controls the respective operation mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to execute the heat treatment of the semiconductor wafer W.

  FIG. 2 is a plan view of the chamber 6. The chamber 6 is configured by mounting a chamber window made of quartz on the upper and lower sides of a cylindrical chamber side wall 61 having a substantially rectangular shape in a plan view. The chamber side wall portion 61 has a substantially cylindrical shape whose upper and lower portions are opened, and the upper chamber window 63 is attached to the upper opening and closed, and the lower chamber window 64 is attached to the lower opening. It is blocked. The chamber side wall 61 is formed of a metal material (for example, stainless steel) excellent in strength and heat resistance.

  The upper chamber window 63 which constitutes the ceiling portion of the chamber 6 is a plate-like member formed of quartz and functions as a quartz window which transmits the flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64 constituting the floor of the chamber 6 is also a plate-like member made of quartz and functions as a quartz window that transmits the light from the halogen heating unit 4 into the chamber 6. An inner space of the chamber 6, that is, a space surrounded by the upper chamber window 63, the lower chamber window 64 and the chamber side wall 61 is defined as a heat treatment space 65.

  Further, on the (+ X) side of the chamber side wall portion 61, a transfer opening (furnace port) 66 for carrying the semiconductor wafer W into and out of the chamber 6 is formed. The transfer opening 66 can be opened and closed by a gate valve (not shown). When the gate valve opens the transfer opening 66, the semiconductor wafer W can be carried into the heat treatment space 65 from the transfer opening 66 and the semiconductor wafer W can be unloaded from the heat treatment space 65. Further, when the gate valve closes the transfer opening 66, the heat treatment space 65 in the chamber 6 is made a closed space.

The heat treatment apparatus 1 further includes a gas supply unit 80 for supplying a treatment gas to the heat treatment space 65 inside the chamber 6, and an exhaust unit 85 for exhausting the chamber 6. The gas supply unit 80 includes a gas supply source 82 and a supply valve 83 in the gas supply pipe 81. The distal end side of the gas supply pipe 81 is in communication with the heat treatment space 65 in the chamber 6, and the proximal end side is connected to the gas supply source 82. A supply valve 83 is interposed in the middle of the path of the gas supply pipe 81. The gas supply source 82 delivers the processing gas to the gas supply pipe 81. The processing gas is supplied to the heat treatment space 65 by opening the supply valve 83. As the gas supply source 82, a gas tank provided in the heat treatment apparatus 1 and a feed pump may be used, or the power of the factory where the heat treatment apparatus 1 is installed may be used. Also good. As a process gas supplied by the gas supply source 82, an inert gas such as nitrogen (N ₂ ), argon (Ar), helium (He), or oxygen (O ₂ ), hydrogen (H ₂ ), chlorine (Cl ₂ ) ), Hydrogen chloride (HCl), ozone (O ₃ ), nitrogen dioxide (N ₂ O), nitrogen monoxide (NO), hydrogen fluoride (HF), fluorine (F ₂ ), nitrogen trifluoride (NF ₃ ) A reactive gas such as ammonia (NH ₃ ) is exemplified, and a mixed gas of these may be used as far as safety permits.

  The exhaust unit 85 includes an exhaust device 87 and an exhaust valve 88 in the gas exhaust pipe 86. The tip end side of the gas exhaust pipe 86 is in communication with the heat treatment space 65 in the chamber 6, and the base end side is connected to the exhaust unit 87. The atmosphere of the heat treatment space 65 is exhausted by opening the exhaust valve 88 while operating the exhaust device 87. As the exhaust device 87, an exhaust utility of a factory in which a vacuum pump or the heat treatment apparatus 1 is installed can be used.

  If the atmosphere of the heat treatment space 65 in the chamber 6 is exhausted by the exhaust unit 85 without supplying the processing gas from the gas supply unit 80 to the chamber 6, the inside of the chamber 6 can be depressurized to less than the atmospheric pressure. The chamber 6 has a pressure-resistant structure capable of depressurizing the inside, and the thickness of the upper chamber window 63 and the lower chamber window 64 of quartz is thicker than the quartz window of the flash lamp annealing apparatus of the normal pressure specification.

  The heat treatment apparatus 1 further includes a susceptor 70 and a lift drive unit 20. The susceptor 70 mounts and supports the semiconductor wafer W to be processed. The susceptor 70 is a substantially rectangular flat member made of quartz. The vertical and horizontal lengths of the susceptor 70 are larger than the diameter of the semiconductor wafer W to be processed (for example, if the diameter of the semiconductor wafer W is φ450 mm, the vertical and horizontal lengths of the susceptor 70 are more than 450 mm) large). On the other hand, as shown in FIG. 2, the planar size of the susceptor 70 is smaller than the planar size of the heat treatment space 65 in the chamber 6.

  FIG. 3 is a cross-sectional view of the susceptor 70. As shown in FIGS. 2 and 3, a wafer pocket 71 is formed at the center of the upper surface of the susceptor 70. The wafer pocket 71 is a circular recess, and its diameter is slightly larger than the diameter of the semiconductor wafer W. Further, the peripheral portion of the wafer pocket 71 is a tapered surface (FIG. 3).

  A support pin 72 is provided upright on the bottom of the wafer pocket 71. In the present embodiment, a total of 12 support pins 72 are erected at every 30 ° along the circumference of the circular wafer pocket 71 and the concentric circle. The diameter of the circle in which the twelve support pins 72 are arranged (the distance between the opposing support pins 72) is smaller than the diameter of the semiconductor wafer W. Each support pin 72 is formed of quartz. The plurality of support pins 72 and the susceptor 70 may be integrally processed, or the support pins 72 separately formed may be welded to the susceptor 70.

  The semiconductor wafer W is supported by point contacts by a plurality of support pins 72 erected in the wafer pocket 71 and mounted on the susceptor 70. The depth of the wafer pocket 71 is larger than the height of the support pin 72. Therefore, displacement of the semiconductor wafer W supported by the support pins 72 is prevented by the tapered surface of the wafer pocket 71 peripheral portion.

  Further, eight through holes 73 are bored in the susceptor 70. Each through hole 73 is provided so as to penetrate the susceptor 70 up and down. Four of the eight through holes 73 are provided on the bottom of the wafer pocket 71, and the remaining four are provided outside the wafer pocket 71. The through hole 73 is a hole through which a delivery pin 12 of the delivery unit 10 described later passes.

  In the heat treatment apparatus 1 according to the present invention, the susceptor 70 is raised and lowered in the chamber 6 by the raising and lowering driving unit 20. One lifting drive unit 20 is provided on each of the (−Y) side and the (+ Y) side of the chamber 6. That is, in the present embodiment, the susceptor 70 is supported on both sides by the two elevation driving units 20 to be elevated and lowered.

  Each elevation drive unit 20 includes a drive motor 21, a support plate 22 and a support shaft 23. The support plate 22 is a metal plate, and its tip is fastened to the end of the susceptor 70 by bolts and nuts. A support shaft 23 is connected to the lower surface of the support plate 22. The drive motor 21 raises and lowers the support plate 22 along the vertical direction (Z-axis direction) by raising and lowering the support shaft 23. As a mechanism by which the drive motor 21 raises and lowers the support shaft 23, for example, a ball screw mechanism in which the drive motor 21 rotates a ball screw screwed to a member connected to the lower end of the support shaft 23 can be used. As the drive motor 21, it is preferable to use a pulse motor capable of accurate positioning control. Further, in order to detect the height position of the susceptor 70, it is preferable to attach an encoder to the drive motor 21.

  As shown in FIG. 1, the elevation driving unit 20 is provided outside the chamber side wall 61 of the chamber 6 except for a part of the tip of the support plate 22. The support plate 22 is provided so as to penetrate an opening formed on the (−Y) side and the (+ Y) side of the chamber side wall 61. In order to maintain the airtightness of the heat treatment space 65, the openings at both ends of the chamber side wall 61 through which the support plate 22 penetrates are covered by the housing 24, and the elevating drive unit 20 is housed inside the housing 24. ing. Therefore, the atmosphere outside the heat treatment apparatus 1 and the heat treatment space 65 are shut off. In order to prevent particles generated by the dust generation of the elevation driving unit 20 itself from flowing into the heat treatment space 65, it is preferable to cover the support shaft 23 and the like with a bellows.

  In the present embodiment, the drive motors 21 of the two elevation drive units 20 provided on the (−Y) side and the (+ Y) side of the chamber 6 synchronously raise and lower the support plate 22. Accordingly, the susceptor 70 is lifted and lowered in the vertical direction by the two lift driving units 20 while the horizontal position (the normal line is in the vertical direction) in the chamber 6.

  The heat treatment apparatus 1 further includes a delivery unit 10 for delivering the semiconductor wafer W to the susceptor 70 in the chamber 6. FIG. 4 is a plan view of the delivery unit 10. The delivery unit 10 includes two arms 11. Two transfer pins 12 are provided upright on each arm 11. Thus, the delivery unit 10 has a total of four delivery pins 12. Each arm 11 is rotatable by a horizontal movement mechanism 13. The horizontal movement mechanism 13 retracts so that the pair of arms 11 does not overlap the semiconductor wafer W held by the susceptor 70 with the semiconductor wafer W held by the susceptor 70 at the delivery operation position (solid line position in FIG. Move horizontally between the position (the position indicated by the two-dot chain line in FIG. 4). The horizontal movement mechanism 13 is provided on the (−X) side of the chamber 6. As the horizontal movement mechanism 13, each arm 11 may be rotated by an individual motor, or a pair of arms 11 may be interlocked and rotated by one motor using a link mechanism. It may be.

  The four transfer pins 12 are moved in the horizontal direction (in the XY plane) by the horizontal movement mechanism 13, but are not moved up and down along the vertical direction. That is, the height positions of the four delivery pins 12 in the chamber 6 are fixed.

  When the susceptor 70 is lowered by the lift drive unit 20 when the pair of arms 11 is closed and located at the delivery operation position, the four delivery pins 12 pass through the through holes 73 formed in the wafer pocket 71. The upper end of the delivery pin 12 protrudes from the upper surface of the susceptor 70. At this time, if the semiconductor wafer W is held in the wafer pocket 71 of the susceptor 70, the semiconductor wafer W is pushed up and supported by the four transfer pins 12. In addition, when the susceptor 70 is lifted with the semiconductor wafer W supported by the four delivery pins 12 protruding from the upper surface of the susceptor 70, the semiconductor wafer W is held in the wafer pocket 71. Thus, the semiconductor wafer W is transferred between the four transfer pins 12 and the susceptor 70.

  On the other hand, when the susceptor 70 is lowered by the lift drive unit 20 when the pair of arms 11 is opened and located at the retracted position, the through holes in which the four delivery pins 12 are provided outside the wafer pocket 71 After passing through 73, the upper end of the delivery pin 12 protrudes from the upper surface of the susceptor 70. At this time, even if the semiconductor wafer W is held by the wafer pocket 71 of the susceptor 70, the semiconductor wafer W is still held by the susceptor 70.

  Returning to FIG. 1, the flash heating unit 5 provided above the chamber 6 is a light source consisting of a plurality (30 in the present embodiment) of xenon flash lamps FL inside the housing 51 and the light source above And a reflector 52 provided to cover the A lamp light emission window 53 is attached to the bottom of the housing 51 of the flash heating unit 5. The lamp light emission window 53 which constitutes the floor of the flash heating unit 5 is a plate-like quartz window formed of quartz. By installing the flash heating unit 5 above the chamber 6, the lamp light emission window 53 faces the upper chamber window 63. The flash lamp FL irradiates the heat treatment space 65 with flash light from above the chamber 6 through the lamp light emission window 53 and the upper chamber window 63.

  The plurality of flash lamps FL are rod-shaped lamps each having a long cylindrical shape, and are arrayed in a planar manner such that their longitudinal directions are parallel to one another along the horizontal direction. Therefore, the plane formed by the arrangement of the flash lamps FL is also a horizontal plane.

  The xenon flash lamp FL has a rod-like glass tube (discharge tube) in which xenon gas is enclosed and an anode and a cathode connected to a capacitor are disposed at both ends, and attached on the outer peripheral surface of the glass tube And a trigger electrode. Since xenon gas is an insulator electrically, no electricity flows in the glass tube under normal conditions even if charge is stored in the capacitor. However, when a high voltage is applied to the trigger electrode to break the insulation, the electricity stored in the capacitor instantaneously flows in the glass tube, and light is emitted by excitation of atoms or molecules of xenon at that time. In such a xenon flash lamp FL, the electrostatic energy stored in advance in the capacitor is converted into an extremely short light pulse of 0.1 milliseconds to 100 milliseconds. It is characterized in that it can emit extremely intense light as compared to a light source. That is, the flash lamp FL is a pulse light emitting lamp that emits light instantaneously in an extremely short time of less than one second. The light emission time of the flash lamp FL can be adjusted by the coil constant of the lamp power supply that supplies power to the flash lamp FL.

  In addition, the reflector 52 is provided above the plurality of flash lamps FL so as to cover the whole of them. The basic function of the reflector 52 is to reflect flash light emitted from a plurality of flash lamps FL to the side of the heat treatment space 65. The reflector 52 is formed of an aluminum alloy plate, and its surface (surface facing the flash lamp FL) is roughened by blasting.

  The halogen heating unit 4 provided below the chamber 6 incorporates a plurality of (40 in the present embodiment) halogen lamps HL inside the housing 41. The halogen heating unit 4 performs light irradiation to the heat treatment space 65 from the lower side of the chamber 6 through the lower chamber window 64 by a plurality of halogen lamps HL.

  FIG. 5 is a plan view showing the arrangement of the plurality of halogen lamps HL. In the present embodiment, the twenty halogen lamps HL are disposed in upper and lower two stages. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The upper and lower portions of the twenty halogen lamps HL are arranged such that their longitudinal directions are parallel to each other along the horizontal direction. Therefore, the plane formed by the arrangement of the halogen lamps HL in the upper and lower stages is a horizontal plane.

  Further, as shown in FIG. 5, the disposition density of the halogen lamps HL in the region facing the peripheral portion is higher than the region facing the central portion of the semiconductor wafer W held by the susceptor 70 in both the upper and lower portions. . That is, in both the upper and lower portions, the disposition pitch of the halogen lamps HL is shorter in the peripheral portion than in the central portion of the lamp arrangement. For this reason, it is possible to perform irradiation of a larger amount of light at the peripheral portion of the semiconductor wafer W which is likely to cause a temperature drop during heating by light irradiation from the halogen heating unit 4.

  Further, a lamp group consisting of the halogen lamp HL in the upper stage and a lamp group consisting of the halogen lamp HL in the lower stage are arranged so as to cross in a lattice shape. That is, a total of 40 halogen lamps HL are disposed such that the longitudinal direction of each halogen lamp HL in the upper stage and the longitudinal direction of each halogen lamp HL in the lower stage are orthogonal to each other.

  The halogen lamp HL is a filament type light source which causes the filament to glow to emit light by energizing the filament disposed inside the glass tube. Inside the glass tube, a gas in which a small amount of a halogen element (iodine, bromine or the like) is introduced into an inert gas such as nitrogen or argon is enclosed. By introducing a halogen element, it is possible to set the temperature of the filament to a high temperature while suppressing the breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a long life and can continuously emit strong light as compared with a normal incandescent lamp. That is, the halogen lamp HL is a continuous lighting lamp which emits light continuously for at least one second or more. Further, since the halogen lamp HL is a rod-like lamp, it has a long life, and by arranging the halogen lamp HL in the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

  Further, in the present embodiment, the light reduction portion 68 is formed on the lower surface of the upper chamber window 63 which is a quartz window closing the upper opening of the chamber 6, and the light amount adjustment portion 69 is formed on the upper surface of the upper chamber window 63. It is provided. That is, the light reduction portion 68 is formed on the opposite surface of the upper chamber window 63 facing the susceptor 70, and the light amount adjustment portion 69 is provided on the surface opposite to the opposite surface.

  FIG. 6 is a view showing the light reducing portion 68 and the light amount adjusting portion 69 provided in the upper chamber window 63. As shown in FIG. FIG. 7 is a plan view of the upper chamber window 63 as viewed from the lower surface side. The light reducing portion 68 in the present embodiment is a rough surface having fine asperities. Therefore, the area of the lower surface of the upper chamber window 63 in which the light reducing portion 68 is formed is in the form of so-called frosted glass (or frosted glass).

  As shown in FIG. 7, the light reducing portion 68 is circularly provided at the center of the lower surface of the upper chamber window 63. The diameter of the circular area of the light reduction portion 68 is smaller than the diameter of the semiconductor wafer W. For example, if the diameter of the semiconductor wafer is φ300 mm, the diameter of the circular area of the light reduction portion 68 is about 200 mm. Further, the central axis of the circular area of the light reducing portion 68 coincides with the central axis of the semiconductor wafer W supported by the susceptor 70. Therefore, the light reducing portion 68 faces the central region except the peripheral portion of the semiconductor wafer W supported by the susceptor 74.

  The light reducing portion 68 may be formed by various known methods for forming the frosted glass, and is formed, for example, by sandblasting the circular area of the upper chamber window 63 shown in FIG. The average surface roughness of the rough surface of the light reduction portion 68 is 0.1 μm or more and 10 μm or less.

  The light reducing portion 68 which is a rough surface having such fine irregularities has a property of scattering light. Of the light emitted from the flash lamp FL and incident on the upper chamber window 63, the light reaching the light reducing portion 68 is scattered by the rough surface having fine irregularities and the light amount is reduced and emitted into the chamber 6 It will be done. That is, the light reduction unit 68 reduces the light emitted from the flash lamp FL into the chamber 6.

  On the other hand, the light amount adjusting portion 69 provided on the upper surface of the upper chamber window 63 is a light shielding plate formed of opaque quartz or the like. Opaque quartz is quartz having minute bubbles. The light shielding plate used as the light amount adjustment unit 69 in the present embodiment does not completely block light (transmission rate 0%), and a certain amount of light in the wavelength range of flash light emitted from the flash lamp FL Permeate. The transmittance of the light amount adjusting unit 69 is defined by the content of air bubbles contained in the opaque quartz material and the thickness of the light amount adjusting unit 69. The shape and size of the light amount adjusting portion 69 are not particularly limited, but in the present embodiment, the shape is a circle slightly larger than the light reducing portion 68. The central axis of the light amount adjustment unit 69 coincides with the central axis of the semiconductor wafer W supported by the susceptor 70. Accordingly, the light amount adjustment unit 69 also faces the central region of the semiconductor wafer W supported by the susceptor 74. The light amount adjusting unit 69 adjusts the light amount of light transmitted from the flash lamp FL to the light amount adjusting unit 69 and incident on the upper chamber window 63. The degree of the adjustment is determined by the transmittance of the light amount adjustment unit 69.

  Further, the control unit 3 controls the above-described various operation mechanisms provided in the heat treatment apparatus 1. The hardware configuration of the control unit 3 is the same as that of a general computer. That is, the control unit 3 includes a CPU that is a circuit that performs various arithmetic processing, a ROM that is a read only memory that stores a basic program, a RAM that is a readable and writable memory that stores various information, control software, data, and the like. It has a magnetic disk to be stored. The CPU of the control unit 3 executes a predetermined processing program to advance the processing in the heat treatment apparatus 1.

  In addition to the above configuration, the heat treatment apparatus 1 prevents excessive temperature rise of the halogen heating unit 4, the flash heating unit 5 and the chamber 6 due to the heat energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W Because of that, it has various cooling structures. For example, the chamber side wall portion 61 is provided with a water cooling pipe (not shown). The halogen heating unit 4 and the flash heating unit 5 have an air cooling structure for exhausting heat by forming a gas flow inside. Air is also supplied to the gap between the upper chamber window 63 and the lamp light emission window 53 to cool the flash heating unit 5 and the upper chamber window 63. Further, the chamber 6 is provided with a temperature sensor (for example, a radiation thermometer that measures temperature without contact) that measures the temperature of the semiconductor wafer W supported by the susceptor 70. Furthermore, the chamber 6 is provided with a pressure sensor that measures the pressure of the heat treatment space 65.

  Next, the processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 will be described. Here, the semiconductor wafer W to be processed is a semiconductor substrate on which a high dielectric constant film is formed as a gate insulating film by a method such as ALD (Atomic Layer Deposition). Since a large number of defects exist in the high dielectric constant film immediately after the film formation, the defects are eliminated by the flash light irradiation heat treatment (annealing) by the heat treatment apparatus 1. The processing procedure of the heat treatment apparatus 1 described below proceeds by the control unit 3 controlling each operation mechanism of the heat treatment apparatus 1.

  First, the transfer opening 66 of the chamber 6 is opened, and the semiconductor wafer W after the high dielectric constant film formation is carried into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus. At this time, the pair of arms 11 of the delivery unit 10 are located at the delivery operation position, the susceptor 70 is lowered, and the four delivery pins 12 pass through the through holes 73 formed in the wafer pocket 71. The upper end of 12 protrudes from the upper surface of the susceptor 70.

  The semiconductor wafer W carried in by the transfer robot advances to a position immediately above the wafer pocket 71 of the susceptor 70 and stops there. Then, as the transfer robot descends, the semiconductor wafer W is transferred from the transfer robot to the four transfer pins 12 and mounted. At this time, the susceptor 70 is positioned at a height between the semiconductor wafer W placed on the delivery pin 12 and the arm 11.

  After the semiconductor wafer W is placed on the delivery pin 12, the transfer robot is withdrawn from the heat treatment space 65, and the transfer opening 66 is closed by the gate valve. Then, as the susceptor 70 is lifted above the delivery pin 12 by the elevation driving unit 20, the semiconductor wafer W placed on the delivery pin 12 is delivered to the susceptor 70. The susceptor 70 mounts and supports the semiconductor wafer W received from the delivery pin 12 in the wafer pocket 71. The semiconductor wafer W is supported by the susceptor 70 with the surface on which the high dielectric constant film is formed as an upper surface.

  After the semiconductor wafer W is delivered to the susceptor 70, the pair of arms 11 is moved to the retracted position by the horizontal movement mechanism 13. Further, the atmosphere inside the chamber 6 is replaced by the gas supply unit 80 and the exhaust unit 85. Specifically, first, the inside of the chamber 6 is temporarily enlarged by exhausting the atmosphere of the heat treatment space 65 in the chamber 6 by the exhaust unit 85 without supplying the processing gas from the gas supply unit 80 to the chamber 6. Reduce pressure below atmospheric pressure. Subsequently, an ammonia atmosphere is formed in the heat treatment space 65 in the chamber 6 by supplying a mixed gas of ammonia and nitrogen as a dilution gas as a processing gas from the gas supply unit 80 while continuing the exhaust by the exhaust unit 85. Do. Thereby, the heat treatment space 65 in the chamber 6 is replaced from the air atmosphere to the ammonia atmosphere. By evacuating the inside of the chamber 6 once and supplying the processing gas, the replacement efficiency can be enhanced. The nitrogen gas supply into the chamber 6 may be started before the transfer opening 66 is opened in order to minimize the inflow of the external atmosphere accompanying the loading of the semiconductor wafer W.

  Next, the control unit 3 controls the elevation driving unit 20 to move the susceptor 70 to a predetermined heat treatment position. The heat treatment position will be described later, but may be below the upper end of the delivery pin 12. In the present embodiment, after the susceptor 70 receives the semiconductor wafer W, the pair of arms 11 is moved to the retracted position, so even if the susceptor 70 is lowered below the upper end of the delivery pin 12, four The delivery pin 12 passes through the through hole 73 provided outside the wafer pocket 71. At this time, the delivery pin 12 projects beyond the upper surface of the susceptor 70, but the semiconductor wafer W is not pushed up by the delivery pin 12, and the semiconductor wafer W is maintained in the state of being held by the susceptor 70.

  After the susceptor 70 holding the semiconductor wafer W reaches the heat treatment position and stops, the 40 halogen lamps HL of the halogen heating unit 4 are simultaneously turned on to start preheating (assist heating). The halogen light emitted from the halogen lamp HL is transmitted from the back surface of the semiconductor wafer W through the lower chamber window 64 and the susceptor 70 formed of quartz. The semiconductor wafer W is preheated by receiving light irradiation from the halogen lamp HL, and the temperature rises. In addition, since the pair of arms 11 of the delivery unit 10 is moved to the retracted position not overlapping the semiconductor wafer W, the halogen lamp HL does not interfere with the preheating.

  When performing preheating with the halogen lamp HL, the temperature of the semiconductor wafer W is measured by a temperature sensor (not shown). The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The control unit 3 controls the output of the halogen lamp HL while monitoring whether or not the temperature of the semiconductor wafer W heated by irradiation of light from the halogen lamp HL has reached a predetermined preheating temperature T1. That is, based on the measurement result by the temperature sensor, the control unit 3 performs feedback control of the output of the halogen lamp HL so that the temperature of the semiconductor wafer W becomes the preheating temperature T1. The preheating temperature T1 is 300 ° C. or more and 600 ° C. or less, and is 450 ° C. in the present embodiment.

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 temporarily maintains the semiconductor wafer W at the preheating temperature T1. Specifically, when the temperature of the semiconductor wafer W measured by the temperature sensor reaches the preheating temperature T1, the control unit 3 controls the output of the halogen lamp HL so that the temperature of the semiconductor wafer W is approximately the preheating temperature T1. Maintained.

  By performing such preheating with the halogen lamp HL, the whole of the semiconductor wafer W is heated to the preheating temperature T1. At the stage of preheating by the halogen lamp HL, the temperature of the peripheral portion of the semiconductor wafer W which is more likely to generate heat tends to be lower than that at the central portion, but the arrangement density of the halogen lamp HL in the halogen heating unit 4 is The region facing the peripheral portion is higher than the region facing the central portion of the semiconductor wafer W. For this reason, the amount of light irradiated to the peripheral portion of the semiconductor wafer W where heat radiation easily occurs is increased, and the non-uniformity of the in-plane temperature distribution of the semiconductor wafer W generated in the preliminary heating stage can be alleviated to some extent.

  When the temperature of the semiconductor wafer W reaches the preheating temperature T1 and a predetermined time has elapsed, flash heat treatment is performed by irradiating a flash light from the flash lamp FL of the flash heating unit 5. At this time, a part of the flash light emitted from the flash lamp FL directly goes into the chamber 6, and the other part is once reflected by the reflector 52 and then goes into the chamber 6, and these flash lights are Flash heating of the semiconductor wafer W is performed by the irradiation.

  Since the flash heating is performed by flash light (flash light) irradiation from the flash lamp FL, the surface temperature of the semiconductor wafer W can be raised in a short time. That is, the flash light emitted from the flash lamp FL has an extremely short irradiation time of 0.1 milliseconds or more and 100 milliseconds or less, in which electrostatic energy previously stored in the capacitor is converted into an extremely short light pulse. It is a strong flashlight. The surface of the semiconductor wafer W including the high dielectric constant film is instantaneously heated to the processing temperature T2 by irradiating the surface of the semiconductor wafer W on which the high dielectric constant film is formed with flash light from the flash lamp FL. Post-deposition thermal processing (PDA) is performed. The processing temperature T2, which is the maximum temperature (peak temperature) reached by the surface of the semiconductor wafer W by flash light irradiation, is 600 ° C. or more and 1200 ° C. or less, and is 1000 ° C. in this embodiment.

  When the surface of the semiconductor wafer W is heated to the processing temperature T2 in an ammonia atmosphere and post-deposition heat treatment is performed, nitridation of the high dielectric constant film is promoted and the high dielectric constant film is present. Defects such as point defects disappear. Since the irradiation time from the flash lamp FL is a short time of about 0.1 milliseconds to 100 milliseconds, the surface temperature of the semiconductor wafer W is raised from the preheating temperature T1 to the processing temperature T2. The time required is also very short, less than one second. The surface temperature of the semiconductor wafer W after flash light irradiation immediately drops rapidly from the processing temperature T2.

  After the flash heating process is completed, the halogen lamp HL is turned off after a predetermined time has elapsed. Thereby, the semiconductor wafer W is rapidly cooled from the preheating temperature T1. Further, the pair of arms 11 is moved from the retracted position to the delivery operation position by the horizontal movement mechanism 13, and the susceptor 70 is lowered. The susceptor 70 is lowered to the height position of the susceptor 70 when the semiconductor wafer W is transferred from the above-described transfer robot to the delivery pin 12. Since the susceptor 70 is lowered with the pair of arms 11 positioned at the delivery operation position, the four delivery pins 12 pass through the through holes 73 provided in the wafer pocket 71. As a result, the semiconductor wafer W held by the susceptor 70 is pushed up from the susceptor 70 and supported by the four transfer pins 12.

  Then, after the temperature of the semiconductor wafer W is lowered to a predetermined temperature or less, the transfer opening 66 of the chamber 6 is opened, and the semiconductor wafer W placed on the delivery pin 12 is unloaded from the chamber 6 by the transfer robot outside the apparatus. The heat treatment of the semiconductor wafer W in the heat treatment apparatus 1 is completed. In addition, before the transfer opening 66 of the chamber 6 is opened, the inside of the chamber 6 is depressurized again to less than the atmospheric pressure by the exhaust unit 85 to discharge the ammonia atmosphere, and then nitrogen gas from the gas supply unit 80 into the chamber 6 It is preferable to pressure the heat treatment space 65 by supplying

  In the present embodiment, the light reducing portion 68 is formed on the lower surface of the upper chamber window 63, and the light amount adjusting portion 69 is provided on the upper surface. Of the flash light emitted from the flash lamp FL during the above-described flash heating process, the light reaching the light amount adjustment unit 69 is reduced in light amount when passing through the light amount adjustment unit 69 and then enters the upper chamber window 63 It will be done. Further, among the light incident on the upper chamber window 63, the light reaching the light reducing portion 68 is reduced in light amount when passing through the light reducing portion 68 and emitted downward from the upper chamber window 63. It becomes. Since both the light reducing portion 68 and the light amount adjusting portion 69 are provided to face the central region of the semiconductor wafer W supported by the susceptor 74, the light amount of the flash light is reduced by the light reducing portion 68 and the light amount adjusting portion 69. As a result of the light reduction, the light amount of the flash light irradiated to the central region except the peripheral portion of the semiconductor wafer W is relatively reduced.

  As described above, at the time of preheating by the halogen lamp HL, the temperature of the peripheral portion of the semiconductor wafer W which tends to release heat tends to be lower than that at the central portion, and even if flash light is irradiated with uniform illuminance at flash heating. The ultimate surface temperature may be lower at the peripheral edge than at the central region. In the present embodiment, the semiconductor wafer at the time of flash heating is relatively reduced by relatively reducing the amount of flash light emitted from the flash lamp FL to the central region of the semiconductor wafer W by the light reduction portion 68 and the light amount adjustment portion 69. The temperature difference between the surface temperature of the peripheral portion of W and the surface temperature of the central portion can be reduced to improve the uniformity of the in-plane temperature distribution.

  By the way, the chamber 6 of the heat treatment apparatus 1 of this embodiment has a pressure-resistant structure capable of reducing pressure, and the thickness of the upper chamber window 63 and the lower chamber window 64 of quartz is that of a conventional flash lamp annealing apparatus of normal pressure specifications. Thicker than stuff. When the thickness of the upper chamber window 63 is increased, as shown in FIG. 6, flash light incident on the upper chamber window 63 from the side of the light amount adjustment unit 69 is multiply reflected between the upper surface and the lower surface of the upper chamber window 63 To reach a position facing the central region of the semiconductor wafer W supported by the susceptor 74. If such flash light is emitted from the lower surface of the upper chamber window 63 toward the semiconductor wafer W as it is, dimming of the flash light irradiated to the central region of the semiconductor wafer W is hindered, and the flash heating is performed. It is inhibited to improve the in-plane temperature distribution uniformity of the surface temperature of the semiconductor wafer W in the above.

  In the present embodiment, since the light reduction portion 68 is provided at the central portion of the lower surface of the upper chamber window 63, flash light which is incident on the upper chamber window 63 from the side of the light amount adjustment portion 69 and repeats multiple reflections. Even if the flashlight reaches a position facing the central region of the semiconductor wafer W supported by the susceptor 74, such flash light is reduced in light amount by the light reduction portion 68 and emitted. As a result, the light quantity of the flash light irradiated to the central region of the semiconductor wafer W is surely reduced, and the uniformity of the in-plane temperature distribution of the semiconductor wafer W at the time of flash heating can be improved. That is, by providing the light reducing portion 68 on the lower surface of the upper chamber window 63, it is possible to improve the uniformity of the in-plane temperature distribution of the semiconductor wafer W during flash heating regardless of the thickness of the upper chamber window 63. It is

  Further, in the present embodiment, the susceptor 70 supporting the semiconductor wafer W can be freely raised and lowered by the raising and lowering drive unit 20, and the heating and lowering drive unit 20 heats the susceptor 70 at a predetermined heat treatment position when heating the semiconductor wafer W. It is moved to Depending on the height position of the susceptor 70, the size of the light reduction region (that is, the region behind the light reduction portion 68) of the flash light on the surface of the semiconductor wafer W supported by the susceptor 70 is different. As the height position of the susceptor 70 increases, the size of the light reduction region on the surface of the semiconductor wafer W increases because the semiconductor wafer W supported by the susceptor 70 approaches the light reduction portion 68. Conversely, as the height position of the susceptor 70 decreases, the size of the light reduction region on the surface of the semiconductor wafer W decreases because the semiconductor wafer W supported by the susceptor 70 moves away from the light reduction portion 68.

  Therefore, the elevation driving unit 20 moves the susceptor 70 to a height position where the size of the light reduction region by the light reduction unit 68 is optimal, thereby making the in-plane temperature distribution of the semiconductor wafer W uniform during flash heating. It can be further improved. Then, such an optimum height position of the susceptor 70 may be set as the above-described heat treatment position. As an example, the height position of the susceptor 70 at which the central portion excluding the peripheral portion of the semiconductor wafer W where the relative temperature decrease is recognized at the time of preheating matches the light reduction region by the light reduction portion 68 is used as the heat treatment apparatus. preferable.

  By combining the light reduction by the light reduction unit 68 formed on the lower surface of the upper chamber window 63 and the elevation of the susceptor 70 by the elevation drive unit 20, the light amount of the flash light irradiated on the surface of the semiconductor wafer W is reduced The degree of freedom in adjusting the light reduction area is increased, and the range of a suitable light reduction area can be easily set.

  Although the embodiments of the present invention have been described above, various modifications can be made to the present invention other than those described above without departing from the scope of the present invention. For example, in the above embodiment, the light reducing portion 68 is formed on the lower surface of the upper chamber window 63 and the light amount adjusting portion 69 is provided on the upper surface, but at least the light reducing portion 68 on the lower surface is provided. Since the flash light traveling toward the central region of the semiconductor wafer W can be reduced after being repeatedly incident on the upper chamber window 63 from the side of the light amount adjustment unit 69 and repeated multiple reflections, the light amount adjustment unit 69 is not necessarily required. It is not a required element. However, when the light amount adjusting portion 69 is provided in combination, it is possible to more effectively reduce the flash light which directly travels from the flash lamp FL to the central region of the semiconductor wafer W.

  Moreover, in the said embodiment, although the light reduction part 68 was made into the rough surface which has fine unevenness | corrugation, it is not limited to this, What is necessary is just the structure which can light-reduce the light quantity of flash light. For example, a mesh or a perforated plate may be used as the light reducing portion 68, and a light shielding plate such as opaque quartz similar to the light amount adjusting portion 69 may be attached to the lower surface of the upper chamber window 63.

  Also, conversely, the light amount adjusting portion 69 provided on the upper surface of the upper chamber window 63 may be roughened similarly to the light reducing portion 68. When a light shielding plate made of opaque quartz or the like is used as the light reduction portion 68 or the light amount adjusting portion 69, the light shielding plate may have a laminated structure. By making the light shielding plate into a laminated structure, it is possible to freely adjust the amount of light transmitted through the light shielding plate.

  Moreover, in the said embodiment, although the whole surface of the area | region where the light reduction part 68 is provided was roughened, a part of the said area | region may be roughened. FIG. 8 is a view showing another example of the light reduction unit 68. As shown in FIG. In the example shown in FIG. 8, a rough surface is formed in a lattice shape in the area of the lower surface of the upper chamber window 63 where the light reducing portion 168 is provided. That is, a rough surface may be formed in part of the area where the light reducing portion 168 is provided. Even with this configuration, the light reduction unit 168 as a whole can reduce the amount of flash light transmitted through the light reduction unit 168. Further, the light reduction rate of the entire light reduction part 168 can also be adjusted by the area ratio in which the rough surface is formed in the area where the light reduction part 168 is provided.

  In addition, a light reduction portion 68 similar to the upper chamber window 63 may be provided on the lower chamber window 64 which is a quartz window for closing the lower opening of the chamber 6. In the case of the lower chamber window 64, the light reduction portion 68 is formed on the upper surface thereof. That is, in any of the upper chamber window 63 and the lower chamber window 64, the light reducing portion 68 is formed on the opposing surface facing the susceptor 70. By providing the light reducing portion 68 on the upper surface of the lower chamber window 64, the amount of light irradiated to the central region of the semiconductor wafer W at the time of preheating is reduced, and the in-plane temperature of the semiconductor wafer W at the preheating stage. The uniformity of distribution can be improved.

  Moreover, in the said embodiment, although 30 flash lamps FL were provided in the flash heating part 5, it is not limited to this, The number of flash lamps FL can be made into arbitrary numbers. . Further, the flash lamp FL is not limited to the xenon flash lamp, and may be a krypton flash lamp. Further, the number of halogen lamps HL provided in the halogen heating unit 4 is not limited to 40, and can be an arbitrary number.

DESCRIPTION OF SYMBOLS 1 heat processing apparatus 3 control part 4 halogen heating part 5 flash heating part 6 chamber 10 delivery part 12 delivery pin 20 raising / lowering drive part 63 upper chamber window 64 lower chamber window 68 light reduction part 69 light quantity adjustment part 70 susceptor 71 wafer pocket 80 gas Supply part 85 Exhaust part FL Flash lamp HL Halogen lamp W Semiconductor wafer

Claims (7)

A heat treatment apparatus for heating a substrate by irradiating the substrate with light,
A chamber for containing a substrate,
A support provided in the chamber for mounting and supporting a substrate;
A quartz window closing the opening of the chamber;
A light irradiation unit provided outside the chamber for irradiating the substrate supported by the support unit via the quartz window with light;
Equipped with
A light reduction unit for reducing light emitted from the light irradiation unit into the chamber is provided on an opposing surface of the quartz window facing the support unit ,
The surface of the quartz window on the opposite side to the opposite surface further includes a circular light amount adjustment unit that adjusts the amount of light incident on the quartz window from the light irradiation unit,
The heat treatment apparatus , wherein the light reduction part has a circular shape smaller than the light amount adjustment part . In the heat treatment apparatus according to claim 1,
A heat treatment apparatus, further comprising: an elevation unit configured to raise and lower the support unit. In the heat treatment apparatus according to claim 1 or 2,
The heat reduction apparatus, wherein the light reduction part is provided at a central part of the facing surface of the quartz window. The heat treatment apparatus according to any one of claims 1 to 3.
The heat treatment apparatus, wherein the light reduction part is a rough surface having unevenness formed on the facing surface. In the heat treatment apparatus according to claim 4,
The heat treatment apparatus, wherein the rough surface is formed in a part of a region where the light reduction part is provided. In the heat treatment apparatus according to any one of claims 1 to 5 ,
The said light irradiation part contains the flash lamp which irradiates flash light, The heat processing apparatus characterized by the above-mentioned. The heat treatment apparatus according to any one of claims 1 to 6 ,
The heat treatment apparatus, wherein the light irradiation unit includes a halogen lamp.

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