JP6486743B2 - Heat treatment apparatus and method for adjusting heat treatment apparatus - Google Patents

Description

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

  In the semiconductor device manufacturing process, impurity introduction is an indispensable step for forming a pn junction in a semiconductor wafer. Currently, impurities are generally introduced by ion implantation and subsequent annealing. The ion implantation method is a technique in which impurity elements such as boron (B), arsenic (As), and phosphorus (P) are ionized and collided with a semiconductor wafer at a high acceleration voltage to physically perform impurity implantation. The implanted impurities are activated by annealing. At this time, if the annealing time is about several seconds or more, the implanted impurity diffuses deeply due to heat, and as a result, the junction depth may become deeper than required, which may hinder the formation of a good device. .

  Therefore, in recent years, flash lamp annealing (FLA) has attracted attention as an annealing technique for heating a semiconductor wafer in an extremely short time. Flash lamp annealing is a semiconductor wafer in which impurities are implanted by irradiating the surface of the semiconductor wafer with flash light using a xenon flash lamp (hereinafter, simply referred to as “flash lamp” means xenon flash lamp). Is a heat treatment technique for raising the temperature of only the surface of the material in a very short time (several milliseconds or less).

  The radiation spectral distribution of a xenon flash lamp ranges from the ultraviolet region to the near infrared region, has a shorter wavelength than the conventional halogen lamp, and almost coincides with the fundamental absorption band of a silicon semiconductor wafer. Therefore, when the semiconductor wafer is irradiated with flash light from the xenon flash lamp, the semiconductor wafer can be rapidly heated with little transmitted light. Further, it has been found that if the flash light irradiation is performed for a very short time of several milliseconds or less, only the vicinity of the surface of the semiconductor wafer can be selectively heated. For this reason, if the temperature is raised for a very short time by a xenon flash lamp, only impurity activation can be performed without deeply diffusing the impurities.

  As a heat treatment apparatus using such a xenon flash lamp, Patent Documents 1 and 2 disclose an apparatus that heats the surface of a semiconductor wafer held by a quartz susceptor having a recess by irradiating flash light from the flash lamp. ing. However, in the apparatuses disclosed in Patent Documents 1 and 2, since the semiconductor wafer is held so that the back surface of the semiconductor wafer is in direct contact with the mounting surface of the susceptor, preheating is performed before flash light irradiation. In addition, the temperature distribution in the wafer surface tends to be non-uniform. Due to such non-uniform temperature distribution in the wafer surface, there are concerns that hot spots and cold spots are scattered in the wafer surface, resulting in deterioration of semiconductor device characteristics and a decrease in manufacturing yield.

  On the other hand, Patent Documents 3 and 4 describe a technique in which a plurality of bumps (support pins) are formed on the upper surface of a flat susceptor, and the surface of a semiconductor wafer supported by the bumps by point contact is irradiated with flash light. Is disclosed. In this way, since the back surface of the semiconductor wafer is not in direct contact with the upper surface of the susceptor, it is possible to suppress the in-plane temperature distribution of the semiconductor wafer from becoming non-uniform in the preheating stage.

JP 2004-179510 A JP 2004-247339 A JP 2009-164451 A JP 2014-120497 A

  By the way, in a heat treatment apparatus using a flash lamp, for example, if the semiconductor wafer is preheated by irradiation with light from a halogen lamp or the like from below, the temperature is likely to decrease at the peripheral edge of the semiconductor wafer where heat easily escapes.

  In order to solve this problem, Patent Document 4 discloses that the arrangement density of a plurality of rod-shaped halogen lamps is increased in a region facing the peripheral portion rather than a region facing the central portion of the semiconductor wafer. It is disclosed that light irradiation with a larger amount of light is performed at the peripheral portion.

  However, it is not easy to make the in-plane temperature distribution of the semiconductor wafer uniform while suppressing temperature drop at the peripheral edge of the semiconductor wafer during preheating only by adjusting the arrangement density of the rod-shaped halogen lamps.

  In addition, for example, when the inside of the chamber is darkened due to dirt due to repeated heating of the substrate coated with various materials, it is not easy to wipe off the dirt completely with a waste cloth or the like. The internal temperature distribution tends to be non-uniform.

  The above problem is not limited to a heat treatment apparatus using a flash lamp, and is common to apparatuses that heat a substrate by light irradiation, including, for example, an RTP (Rapid Thermal Process) apparatus using a halogen lamp.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of achieving a uniform in-plane temperature distribution of a substrate during heating by light irradiation in a heat treatment apparatus.

In order to solve the above problem, a heat treatment apparatus according to a first aspect is a heat treatment apparatus that heats a substrate by irradiating the substrate with light, and includes a holding unit that holds the substrate, and a plurality of lamps. And an irradiation unit that heats the substrate by irradiating the substrate with light emitted from the plurality of lamps, and the irradiation unit is disposed on the opposite side of the plurality of lamps from the substrate. heating and a reflection portion for reflecting light emitted from the plurality of lamps toward the substrate, by a first irradiation of said substrate held on and included in the plurality of lamps the holding unit light A plurality of first lamps; and a second lamp that is not included in the plurality of lamps and that heats the substrate held by the holding unit by a second irradiation of light . Is the second irradiation The plurality of first lamps preliminarily heats the substrate held by the holding unit by the first irradiation before heating by the second irradiation, and the reflection unit includes: Each of the first lamps of the plurality of first lamps includes a reflector that reflects light emitted from the first lamp toward the substrate, or two of the plurality of first lamps A reflector for reflecting light emitted from the two or more first lamps toward the substrate for each first lamp group including one or more first lamps; and for each of the first lamps, the reflector and the By changing the angular relationship with one first lamp, the direction in which the light from the one first lamp is reflected by the reflector is changed, or for each first lamp group, the reflector and Previous By angular relationship between two or more first lamp is changed, the light from the two or more first lamp and a direction that is reflected by the reflector is changed.

A heat treatment apparatus according to a second aspect is the heat treatment apparatus according to the first aspect, wherein the second lamp heats the substrate held by the holding portion by the second irradiation with flash light. A lamp is included.

A heat treatment apparatus according to a third aspect is the heat treatment apparatus according to the second aspect, wherein the substrate is a semiconductor substrate in which impurities are implanted into a surface portion, and the heat treatment apparatus includes the first irradiation and The actual in-plane distribution of sheet resistance in the surface portion of the semiconductor substrate after being heated by the second irradiation, and a preset reference for the in-plane distribution of sheet resistance in the surface portion of the semiconductor substrate; The angle relationship between the reflector and the first lamp is changed for each of the first lamps, or the reflector is changed for each of the first lamp groups according to the relationship with the distribution in the reference plane. And a controller that changes an angular relationship with the two or more first lamps .

A heat treatment apparatus according to a fourth aspect is the heat treatment apparatus according to the third aspect, wherein the control unit has a surface portion of the semiconductor substrate after the first irradiation and the second irradiation are performed. The amount of light emitted from the irradiating unit is increased in a region where the sheet resistance value in the actual in-plane distribution is higher than the sheet resistance value in the reference in-plane distribution. The angle relationship between the reflector and the one first lamp is changed for each one first lamp, or the angle relationship between the reflector and the two or more first lamps for each first lamp group. It is characterized by changing.

A heat treatment apparatus according to a fifth aspect is the heat treatment apparatus according to the fourth aspect, wherein the control unit is configured to change the one in accordance with a difference between the actual in-plane distribution and the reference in-plane distribution . Changing the angular relationship between the reflector and the one first lamp for each first lamp, or changing the angular relationship between the reflector and the two or more first lamps for each first lamp group. It is characterized by.

A method for adjusting a heat treatment apparatus according to a sixth aspect is a method for adjusting a heat treatment apparatus for heating a semiconductor substrate by irradiating light onto a semiconductor substrate into which impurities have been implanted, wherein (a) the semiconductor substrate is (B) preliminarily heating the substrate held by the holding unit by first irradiation with light from a plurality of first lamps, and Heating the semiconductor substrate by a second irradiation of flash light by a second lamp after the start of a typical heating, and (c) the first irradiation and the second irradiation in the step (b) Obtaining an actual in-plane distribution of the sheet resistance at the surface portion of the semiconductor substrate by measuring the sheet resistance at the surface portion of the semiconductor substrate after being irradiated; and (d) the step (c) In The actual plane distribution obtained have been, in response to said relationship between the reference plane distribution as a predetermined reference for the in-plane distribution of the sheet resistance at the surface portion of the semiconductor substrate, the plurality of first ramp For each of the first lamps, the angle relationship between the first lamp and the reflector that reflects the light emitted from the first lamp toward the semiconductor substrate is changed, or the plurality A reflector for reflecting light emitted from the two or more first lamps toward the semiconductor substrate for each first lamp group including two or more first lamps of the first lamps; and the two or more lamps Changing the angular relationship with the first lamp.

The heat treatment apparatus adjustment method according to a seventh aspect is the heat treatment apparatus adjustment method according to the sixth aspect, wherein the first irradiation and the second irradiation are performed in the step (d). From the plurality of first lamps to a region having a higher sheet resistance value in the actual in-plane distribution than the sheet resistance value in the reference in-plane distribution in the subsequent surface portion of the semiconductor substrate A reflector for reflecting the light emitted from the first lamp toward the semiconductor substrate for each first lamp of the plurality of first lamps so that the amount of light to be irradiated is increased ; From each of the two or more first lamps, the angle relationship with the one first lamp is changed, or for each first lamp group including two or more first lamps of the plurality of first lamps. Light emitted from the semiconductor substrate Only and changes the angular relationship between the reflector and the two or more first lamp for reflecting.

A method for adjusting a heat treatment apparatus according to an eighth aspect is the method for adjusting a heat treatment apparatus according to the seventh aspect, wherein the step (d) is the actual step acquired in (d1) step (c). Calculating a difference between the in-plane distribution and the reference in-plane distribution; and (d2) a first one of the plurality of first lamps according to the difference calculated in the step (d1). For each lamp, change the angular relationship between the first lamp and the reflector that reflects the light emitted from the one first lamp toward the semiconductor substrate, or one of the plurality of first lamps For each first lamp group including two or more first lamps, an angle between the reflector that reflects light emitted from the two or more first lamps toward the semiconductor substrate and the two or more first lamps. Changing the relationship And butterflies.

With the heat treatment apparatus according to any one of the first to fifth aspects, the light from the lamp is changed by changing the angular relationship between the lamp and at least a part of the reflecting portion that reflects the light emitted from the lamp toward the substrate. Since the direction in which the light is reflected is changed, the in-plane temperature distribution of the substrate can be made uniform during heating by light irradiation in the heat treatment apparatus.

In the heat treatment apparatus according to any one of the first to fifth aspects, the substrate is preliminarily heated by the first irradiation of light by the first lamp, and after the preliminary heating is started, the light of the second lamp is emitted. Since the substrate starts to be heated by the second irradiation, the in-plane temperature distribution of the substrate can be made uniform during the preheating by the light irradiation in the heat treatment apparatus.

In the heat treatment apparatus according to any of the second to fifth aspects, the substrate is heated by the irradiation of flash light by the second lamp after the substrate starts to be preliminarily heated by the irradiation of light by the first lamp. In the heat treatment apparatus that heats the substrate by irradiation with flash light, the in-plane temperature distribution of the substrate can be made uniform during preheating by light irradiation.

After any of the heat treatment apparatuses according to the third to fifth aspects and the adjustment methods of the heat treatment apparatuses according to the sixth to eighth aspects, the semiconductor substrate is preliminarily heated and heated by flash light irradiation. In accordance with the relationship between the in-plane distribution of the sheet resistance in the surface portion of the semiconductor substrate and the in-plane distribution serving as a reference for the sheet resistance, the angular relationship between at least a part of the reflecting portion and the first lamp is changed, In the heat treatment apparatus that heats the substrate by irradiation with flash light, the in-plane temperature distribution of the semiconductor substrate can be made more uniform during preheating by light irradiation.

Region in which sheet resistance increases in the surface portion of the semiconductor substrate after the heat treatment is performed by any of the heat treatment apparatus according to the fourth and fifth aspects and the adjustment method of the heat treatment apparatus according to the seventh and eighth aspects. On the other hand, since irradiation with a larger amount of light is performed, the in-plane temperature distribution of the semiconductor substrate can be made more appropriate during preheating by light irradiation.

It is a longitudinal cross-sectional view which shows the structure of the heat processing apparatus which concerns on one Embodiment. It is a perspective view which shows the whole external appearance of a holding | maintenance part. It is the top view which looked at the susceptor of the holding | maintenance part from the upper surface. It is sectional drawing which shows the cross section of a holding part typically. It is the figure which expanded the installation part of the guide ring. It is a top view of a transfer mechanism. It is a side view of a transfer mechanism. It is a top view which shows arrangement | positioning of a some halogen lamp. It is sectional drawing which shows typically arrangement | positioning of the reflection part with respect to each halogen lamp. It is a figure which shows typically a mode that the angle of a reflector is changed. It is a flowchart which concerns on the adjustment method of a heat processing apparatus. It is a flowchart which concerns on the adjustment method of a heat processing apparatus. It is sectional drawing which illustrates arrangement | positioning of the reflection part which concerns on one modification. It is a figure which illustrates a mode that the angle of the reflector which concerns on one modification is changed.

  Hereinafter, an embodiment and various modifications will be described with reference to the drawings. In the drawings, parts having the same configuration and function are denoted by the same reference numerals, and redundant description is omitted in the following description. In FIG. 1 and the subsequent drawings, the dimensions and the number of each part are exaggerated or simplified as necessary for easy understanding.

  FIG. 1 is a longitudinal sectional view showing a configuration of a heat treatment apparatus 1 according to an embodiment. The heat treatment apparatus 1 is an apparatus that heats a semiconductor wafer W by irradiating the semiconductor wafer W as a substrate with light. Specifically, the heat treatment apparatus 1 is an apparatus that heats the semiconductor wafer W by irradiating the semiconductor wafer W with flash light (also referred to as a flash lamp annealing apparatus). Here, the semiconductor wafer W to be processed generally has a disk shape. The size of the semiconductor wafer W is not particularly limited. For example, a semiconductor wafer having a diameter of 300 mm or 450 mm can be adopted. Impurities are implanted into a portion (also referred to as a surface portion) in the vicinity of the surface of the semiconductor wafer W carried into the heat treatment apparatus 1, and the activation process of the impurities implanted by the heat treatment by the heat treatment apparatus 1 is executed. Is done.

  The heat treatment apparatus 1 includes a chamber 6 that accommodates a semiconductor wafer W, a flash heating unit 5 that houses a plurality of flash lamps FL, and a halogen heating unit 4 that serves as an irradiation unit that houses a plurality of halogen lamps HL. Specifically, the flash heating unit 5 is provided above the chamber 6, and the halogen heating unit 4 is provided below the chamber 6. In addition, the heat treatment apparatus 1 includes a holding unit 7 and a transfer mechanism 10 inside the chamber 6. The holding unit 7 is a part that holds the semiconductor wafer W, and holds the semiconductor wafer W in a horizontal posture, for example. The transfer mechanism 10 is a mechanism that transfers the semiconductor wafer W between the holding unit 7 and the outside of the apparatus. Furthermore, the heat treatment apparatus 1 includes a control unit 3 that controls the operation mechanisms provided in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 to perform the heat treatment of the semiconductor wafer W.

  The chamber 6 is configured by attaching quartz chamber windows to upper and lower portions of the cylindrical chamber side portion 61. The chamber side portion 61 has a substantially cylindrical shape with an upper and lower opening. The upper opening of the chamber side portion 61 is closed by mounting the upper chamber window 63, and the lower opening of the chamber side portion 61 is lower. The side chamber window 64 is closed. The upper chamber window 63 that constitutes the ceiling of the chamber 6 is a disk-shaped member made of quartz, and functions as a quartz window that transmits the flash light emitted from the flash heating unit 5 into the chamber 6. The lower chamber window 64 constituting the floor portion of the chamber 6 is also a disk-shaped member made of quartz, and functions as a quartz window that transmits light from the halogen heating unit 4 into the chamber 6.

  Further, a reflection ring 68 is attached to the upper part of the inner wall surface of the chamber side part 61, and a reflection ring 69 is attached to the lower part of the inner wall surface of the chamber side part 61. The reflection rings 68 and 69 are both formed in an annular shape. The upper reflection ring 68 is mounted by being fitted into the chamber side portion 61 from above. On the other hand, the lower reflecting ring 69 is mounted by being fitted into the chamber side portion 61 from the lower side and fastened with a screw (not shown). That is, the reflection rings 68 and 69 are both detachably attached to the chamber side portion 61. An inner space of the chamber 6, that is, a space surrounded by the upper chamber window 63, the lower chamber window 64, the chamber side portion 61, and the reflection rings 68 and 69 is defined as a heat treatment space 65.

  Here, the recesses 62 are formed on the inner wall surface of the chamber 6 by attaching the reflection rings 68 and 69 to the chamber side portion 61. That is, a recess 62 surrounded by a central portion of the inner wall surface of the chamber side portion 61 where the reflecting rings 68 and 69 are not mounted, a lower end surface of the reflecting ring 68, and an upper end surface of the reflecting ring 69 is formed. The The recess 62 is formed in an annular shape along the horizontal direction on the inner wall surface of the chamber 6, and surrounds the holding portion 7 that holds the semiconductor wafer W.

  The chamber side portion 61 and the reflection rings 68 and 69 are formed of a metal material (for example, stainless steel) having excellent strength and heat resistance. Further, the inner peripheral surfaces of the reflection rings 68 and 69 are mirrored by electrolytic nickel plating.

  The chamber side 61 is formed with a transfer opening (furnace port) 66 for carrying the semiconductor wafer W into and out of the chamber 6. The transfer opening 66 can be opened and closed by a gate valve 185. The transport opening 66 is connected to the outer peripheral surface of the recess 62. For this reason, when the gate valve 185 opens the transfer opening 66, the semiconductor wafer W is transferred from the transfer opening 66 to the heat treatment space 65 through the recess 62 and the semiconductor from the heat treatment space 65 through the recess 62. The wafer W can be carried out. Further, when the gate valve 185 closes the transfer opening 66, the heat treatment space 65 in the chamber 6 becomes a sealed space.

Further, a gas supply hole 81 for supplying a processing gas (nitrogen gas (N ₂ ) in the present embodiment) to the heat treatment space 65 is formed in the upper portion of the inner wall of the chamber 6. The gas supply hole 81 is formed at a position above the recess 62 and may be provided in the reflection ring 68. The gas supply hole 81 is connected to a gas supply pipe 83 through a buffer space 82 formed in an annular shape inside the side wall of the chamber 6. The gas supply pipe 83 is connected to a gas supply source 85. A valve 84 is inserted in the middle of the path of the gas supply pipe 83. When the valve 84 is opened, nitrogen gas is supplied from the gas supply source 85 to the buffer space 82. The nitrogen gas flowing into the buffer space 82 flows so as to expand in the buffer space 82 having a smaller fluid resistance than the gas supply hole 81 and is supplied from the gas supply hole 81 into the heat treatment space 65. Note that the processing gas is not limited to nitrogen gas, and an inert gas such as argon (Ar) and helium (He), or oxygen (O ₂ ), hydrogen (H ₂ ), chlorine (Cl ₂ ), A reactive gas such as hydrogen chloride (HCl), ozone (O ₃ ), and ammonia (NH ₃ ) may be used.

  On the other hand, a gas exhaust hole 86 for exhausting the gas in the heat treatment space 65 is formed in the lower portion of the inner wall of the chamber 6. The gas exhaust hole 86 is formed at a position below the recess 62 and may be provided in the reflection ring 69. The gas exhaust hole 86 is connected to a gas exhaust pipe 88 through a buffer space 87 formed in an annular shape inside the side wall of the chamber 6. The gas exhaust pipe 88 is connected to the exhaust unit 190. A valve 89 is inserted in the middle of the path of the gas exhaust pipe 88. When the valve 89 is opened, the gas in the heat treatment space 65 is discharged from the gas exhaust hole 86 to the gas exhaust pipe 88 through the buffer space 87. Each of the gas supply holes 81 and the gas exhaust holes 86 may be provided in a plurality along the circumferential direction of the chamber 6 or may be slit-shaped. Further, the gas supply source 85 and the exhaust unit 190 may be a mechanism provided in the heat treatment apparatus 1 or may be a utility of a factory where the heat treatment apparatus 1 is installed.

  A gas exhaust pipe 191 that exhausts the gas in the heat treatment space 65 is also connected to the tip of the transfer opening 66. The gas exhaust pipe 191 is connected to the exhaust unit 190 via a valve 192. By opening the valve 192, the gas in the chamber 6 is exhausted through the transfer opening 66.

  FIG. 2 is a perspective view showing the overall appearance of the holding unit 7. 3 is a plan view of the susceptor 74 of the holding unit 7 as viewed from above, and FIG. 4 is a cross-sectional view schematically showing a cross section of the holding unit 7 along a plane perpendicular to the horizontal plane. In FIG. 4, the outer edge of the semiconductor wafer W held by the holding unit 7 is drawn with a two-dot chain line. The holding part 7 includes a base ring 71, a connecting part 72, and a susceptor 74. The base ring 71, the connecting portion 72, and the susceptor 74 are all made of quartz. That is, the whole holding part 7 is made of quartz.

  The base ring 71 is a ring-shaped quartz member. The base ring 71 is supported on the wall surface of the chamber 6 by being placed on the bottom surface of the recess 62 (see FIG. 1). On the upper surface of the base ring 71 having an annular shape, a plurality of connecting portions 72 (four in this embodiment) are erected along the circumferential direction. The connecting portion 72 is also a quartz member, and is fixed to the base ring 71 by welding. The shape of the base ring 71 may be, for example, an arc shape in which a part is omitted from the annular shape.

  The susceptor 74 holds the semiconductor wafer W placed on the susceptor 74 in the chamber 6. The susceptor 74 is supported by four connecting portions 72 provided on the base ring 71. The susceptor 74 includes a holding plate 75 as a plate, a guide ring 76 as a guide portion, and a plurality of support pins 77. The holding plate 75 is a circular flat plate member made of quartz. The diameter of the holding plate 75 is larger than the diameter of the semiconductor wafer W. That is, the holding plate 75 has a larger planar size than the semiconductor wafer W.

  A guide ring 76 is installed on the peripheral edge of the upper surface of the holding plate 75. The guide ring 76 is an annular member having an inner diameter larger than the diameter of the semiconductor wafer W. Further, the guide ring 76 is made of quartz, like the holding plate 75. The guide ring 76 may be welded to the upper surface of the holding plate 75, or may be fixed to the holding plate 75 with a pin or the like formed separately. Alternatively, the guide ring 76 may simply be placed on the peripheral edge of the upper surface of the holding plate 75. Here, when the guide ring 76 is welded to the holding plate 75, generation of particles due to sliding of the quartz member is suppressed, and when the guide ring 76 is placed, distortion of the holding plate 75 due to welding is prevented. Can be done.

  FIG. 5 is an enlarged view of a portion where the guide ring 76 is installed. The inner periphery of the guide ring 76 is a tapered surface 76 a that widens upward from the holding plate 75. Of the upper surface of the holding plate 75, a region inside the tip (lower end) of the tapered surface 76a is a mounting surface 75a on which the semiconductor wafer W is mounted. The gradient α of the tapered surface 76a of the guide ring 76 with respect to the mounting surface 75a of the holding plate 75 is 30 ° or more and 70 ° or less (45 ° in this embodiment). Further, the surface average roughness (Ra) of the tapered surface 76a is set to 1.6 μm or less.

  The inner diameter of the guide ring 76 (the diameter of the tip of the tapered surface 76a) is 10 mm or more and 40 mm or less larger than the diameter of the semiconductor wafer W. Therefore, when the semiconductor wafer W is held at the center of the mounting surface 75a of the holding plate 75, the distance from the outer peripheral end of the semiconductor wafer W to the tip of the tapered surface 76a is 5 mm or more and 20 mm or less. In this embodiment, the inner diameter of the guide ring 76 is set to φ320 mm with respect to the semiconductor wafer W of φ300 mm (the distance from the outer peripheral end of the semiconductor wafer W to the tip of the tapered surface 76a is 10 mm). The outer diameter of the guide ring 76 is not particularly limited, but may be the same as the diameter of the holding plate 75 (φ340 mm in the present embodiment), for example.

  A plurality of support pins 77 are erected on the mounting surface 75 a of the holding plate 75. In the present embodiment, a total of six support pins 77 are erected every 60 ° along a circumference that is concentric with the outer circumference of the placement surface 75a (the inner circumference of the guide ring 76). The diameter of the circle in which the six support pins 77 are arranged (the distance between the support pins 77 facing each other) is smaller than the diameter of the semiconductor wafer W, and is 280 mm in this embodiment. Each support pin 77 is made of quartz. The plurality of support pins 77 may be erected by being fitted into a recess formed in the upper surface of the holding plate 75.

  The four connecting portions 72 erected on the base ring 71 and the lower peripheral edge portion of the holding plate 75 of the susceptor 74 are fixed by welding. That is, the susceptor 74 and the base ring 71 are fixedly connected by the connecting portion 72. When the base ring 71 of the holding unit 7 is supported on the wall surface of the chamber 6, the holding unit 7 is attached to the chamber 6. In a state where the holding unit 7 is mounted on the chamber 6, the holding plate 75 of the susceptor 74 assumes a horizontal posture (a posture in which the normal line matches the vertical direction). The semiconductor wafer W carried into the chamber 6 is placed and held in a horizontal posture on the susceptor 74 of the holding unit 7 attached to the chamber 6. At this time, the semiconductor wafer W is held by the susceptor 74 by being supported by point contact by a plurality of support pins 77 erected on the holding plate 75. That is, the semiconductor wafer W is supported by the plurality of support pins 77 at a predetermined interval from the mounting surface 75 a of the holding plate 75. Further, the thickness of the guide ring 76 is larger than the height of the support pin 77. Accordingly, the position shift in the horizontal direction of the semiconductor wafer W supported by the support pins 77 is prevented by the guide ring 76.

  As shown in FIGS. 2 and 3, the holding plate 75 of the susceptor 74 has an opening 78 penetrating vertically. The opening 78 is provided so that radiation light (infrared light) emitted from the lower surface of the semiconductor wafer W held by the susceptor 74 is received by the radiation thermometer 120. That is, the light emitted from the back surface of the semiconductor wafer W held by the susceptor 74 is received by the radiation thermometer 120 through the opening 78, and the temperature of the semiconductor wafer W is measured by a separate detector. Further, four through-holes 79 are formed in the holding plate 75 of the susceptor 74 so that lift pins 12 of the transfer mechanism 10 (to be described later) can pass therethrough for delivery of the semiconductor wafer W.

  FIG. 6 is a plan view of the transfer mechanism 10. FIG. 7 is a side view of the transfer mechanism 10. The transfer mechanism 10 includes two transfer arms 11. The transfer arm 11 has an arc shape that follows the generally annular recess 62. Two lift pins 12 are erected on each transfer arm 11. Each transfer arm 11 can be rotated by a horizontal movement mechanism 13. The horizontal moving mechanism 13 holds the pair of transfer arms 11 in the holding unit 7 and a transfer operation position (a position drawn by a solid line in FIG. 6) for transferring the semiconductor wafer W to the holding unit 7. The semiconductor wafer W is horizontally moved between a retracted position (a position drawn by a two-dot chain line in FIG. 6) that does not overlap with the semiconductor wafer W in plan view. As the horizontal movement mechanism 13, each transfer arm 11 may be rotated by an individual motor, or a pair of transfer arms 11 may be interlocked by a single motor using a link mechanism. It may be moved.

  The pair of transfer arms 11 are moved up and down together with the horizontal moving mechanism 13 by the lifting mechanism 14. When the elevating mechanism 14 raises the pair of transfer arms 11 at the transfer operation position, a total of four lift pins 12 are through holes 79 formed in the holding plate 75 of the susceptor 74 (see FIGS. 2 and 3). , And the upper end of the lift pin 12 protrudes from the upper surface of the holding plate 75. On the other hand, when the elevating mechanism 14 lowers the pair of transfer arms 11 at the transfer operation position, the lift pins 12 are extracted from the through holes 79, and the horizontal movement mechanism 13 moves the pair of transfer arms 11 so as to open each of them. The transfer arm 11 moves to the retracted position. The retracted position of the pair of transfer arms 11 is directly above the base ring 71 of the holding unit 7. Since the base ring 71 is placed on the bottom surface of the recess 62, the retracted position of the transfer arm 11 is inside the recess 62. Note that an exhaust mechanism (not shown) is also provided in the vicinity of the portion where the drive unit (the horizontal movement mechanism 13 and the lifting mechanism 14) of the transfer mechanism 10 is provided, and the atmosphere around the drive unit of the transfer mechanism 10 Is discharged to the outside of the chamber 6.

  Returning to FIG. 1, the flash heating unit 5 is provided above the chamber 6. Inside the housing 51, a light source including a plurality of (30 in the present embodiment) flash lamps FL and the light source And a reflector 52 provided to cover the top. Then, the flash heating unit 5 heats the semiconductor wafer W by irradiating the semiconductor wafer W held by the susceptor 74 with flash light emitted from a plurality of flash lamps FL. In the present embodiment, a xenon flash lamp is employed as the flash lamp FL. A lamp light emission window 53 is mounted on the bottom of the casing 51 of the flash heating unit 5. The lamp light emission window 53 constituting the floor of the flash heating unit 5 is a plate-like quartz window made 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 the longitudinal direction of each of the flash lamps FL is along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). ) They are arranged in a plane so as to be parallel to each other. 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-shaped glass tube (discharge tube) in which xenon gas is sealed and an anode and a cathode connected to a capacitor at both ends thereof, and an outer peripheral surface of the glass tube. And a triggered electrode. Since xenon gas is an electrical insulator, electricity does not flow into the glass tube under normal conditions even if electric charges are accumulated in the capacitor. However, when the insulation is broken by applying a high voltage to the trigger electrode, the electricity stored in the capacitor flows instantaneously 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 previously stored in the capacitor is converted into an extremely short light pulse of 0.1 to 100 milliseconds, so that the continuous lighting like the halogen lamp HL is possible. It has the characteristic that it can irradiate extremely strong light compared with a light source.

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

  The halogen heating unit 4 is provided below the chamber 6, and is provided so as to cover a plurality of (in this embodiment, 40) halogen lamps HL as first lamps and to cover the light source from below. And a reflecting portion 4R. The halogen heating unit 4 irradiates the heat treatment space 65 with light emitted from the plurality of halogen lamps HL from below the chamber 6 through the lower chamber window 64. Here, the reflecting portion 4R is disposed on the opposite side of the plurality of halogen lamps HL from the semiconductor wafer W. For this reason, light emitted from the plurality of halogen lamps HL toward the reflecting portion 4R is reflected toward the semiconductor wafer W by the reflecting portion 4R. In this way, the light emitted from the plurality of halogen lamps HL is irradiated onto the semiconductor wafer W held by the susceptor 74, and as a result, the semiconductor wafer W is heated.

  FIG. 8 is a plan view showing the arrangement of a plurality of halogen lamps HL. In the present embodiment, 20 halogen lamps HL are arranged in two upper and lower stages. Each halogen lamp HL is a rod-shaped lamp having a long cylindrical shape. The 20 halogen lamps HL in both the upper and lower stages are arranged so that their longitudinal directions are parallel to each other along the main surface of the semiconductor wafer W held by the holding unit 7 (that is, along the horizontal direction). Yes. Therefore, the plane formed by the arrangement of the halogen lamps HL in both the upper stage and the lower stage is a horizontal plane.

  Further, as shown in FIG. 8, the arrangement 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 holding portion 7 in both the upper and lower steps. ing. That is, in both the upper and lower stages, the arrangement pitch of the halogen lamps HL is shorter in the peripheral part than in the central part of the lamp array. For this reason, it is possible to irradiate a larger amount of light to the peripheral portion of the semiconductor wafer W where the temperature is likely to decrease during heating by irradiation with light from the halogen heating unit 4.

  Further, the lamp group composed of the upper halogen lamp HL and the lamp group composed of the lower halogen lamp HL are arranged so as to intersect in a lattice pattern. That is, a total of 40 halogen lamps HL are arranged so that the longitudinal direction of the upper halogen lamps HL and the longitudinal direction of the lower halogen lamps HL are orthogonal to each other.

  The halogen lamp HL is a filament-type light source that emits light by making the filament incandescent by energizing the filament disposed inside the glass tube. Inside the glass tube, a gas obtained by introducing a trace amount of a halogen element (iodine, bromine, etc.) into an inert gas such as nitrogen or argon is enclosed. By introducing a halogen element, it is possible to set the filament temperature to a high temperature while suppressing breakage of the filament. Therefore, the halogen lamp HL has a characteristic that it has a longer life than a normal incandescent bulb and can continuously radiate strong light. Further, since the halogen lamp HL is a rod-shaped lamp, it has a long life, and by arranging the halogen lamp HL along the horizontal direction, the radiation efficiency to the upper semiconductor wafer W becomes excellent.

  FIG. 9 is a cross-sectional view schematically showing the arrangement of the reflecting portion 4R. FIG. 10 is a cross-sectional view schematically showing how the reflector 4Rf rotates. 9 and 10, the traveling direction of the light emitted from each halogen lamp HL is indicated by an arrow drawn by a thin linear line.

  In the present embodiment, the reflector 4R is provided with one reflector 4Rf for each halogen lamp HL. Specifically, as shown in FIG. 9, a semi-cylindrical reflector 4Rf is provided so as to cover the lower half of the halogen lamp HL that extends downward from the side. In FIG. 9, as an example, in each of the six halogen lamps HL <b> 1 to HL <b> 6 arranged in parallel to each other, the lower half portion extending from the side downward is covered with the reflectors 4 </ b> Rf <b> 1 to 4 </ b> Rf <b> 6. It is shown. Although the light from the halogen lamp HL is normally scattered in all directions, as described above, the reflector 4Rf is provided so as to surround the lower half of the halogen lamp HL, so that directivity is given to the light emitted from the halogen lamp HL. Is held.

  Moreover, in the halogen heating part 4, each reflector 4Rf1-4Rf6 is provided rotatably, for example. Specifically, a reflector 4Rf provided for each halogen lamp HL is rotatably provided around the axis of each cylindrical halogen lamp HL. Thereby, the angular relationship between the reflectors 4Rf1 to 4Rf6 as at least a part of the reflecting portion 4R and the plurality of halogen lamps HL can be changed. As a result, the direction in which the light from at least some of the plurality of halogen lamps HL is reflected by the reflecting portion 4R can be changed. Thereby, in the heat processing apparatus 1, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during heating by light irradiation.

  FIG. 10 shows how the angular relationship between the three reflectors 4Rf1 to 4Rf3 and the three halogen lamps HL1 to HL3 as a part of the reflecting portion 4R is changed. Here, the direction in which the reflector 4Rf rotates is indicated by a solid arrow.

  In this embodiment, the semiconductor wafer W held by the holding unit 7 is irradiated with light from the halogen lamp HL as the first lamp (also referred to as first irradiation), and the flash lamp as the second lamp. It is started before the flash light irradiation by FL (also referred to as second irradiation). Accordingly, the semiconductor wafer W held by the holding unit 7 by the plurality of halogen lamps HL is preliminarily preliminarily irradiated with light from the halogen lamp HL before being heated by the second irradiation of light from the flash lamp FL. Can be heated. That is, the semiconductor wafer W is preliminarily heated by the first irradiation of light from the halogen lamp HL, and after the preliminary heating is started, the semiconductor wafer W is heated by the second irradiation of flash light by the flash lamp FL. start. As a result, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during preheating by light irradiation in the heat treatment apparatus 1. In the present embodiment, a configuration is adopted in which the second irradiation with the flash light is started from the middle of the first irradiation.

  In the present embodiment, in particular, the semiconductor wafer W held on the holding unit 7 by the flash lamp FL is irradiated with flash light, so that the semiconductor wafer W is preliminarily irradiated by the light irradiation by the halogen lamp HL. After starting to be heated, the semiconductor wafer W is heated by irradiation with flash light from the flash lamp FL. Thereby, in the heat treatment apparatus 1 that heats the semiconductor wafer W by irradiation with flash light, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during preheating by light irradiation. As a result, when the semiconductor wafer W is heated by the second irradiation of flash light from the flash lamp FL, the in-plane temperature distribution of the semiconductor wafer W can be made uniform.

  The control unit 3 controls the various operation mechanisms provided in the heat treatment apparatus 1. The configuration of the control unit 3 as hardware is the same as that of a general computer. That is, the control unit 3 stores a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, 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 keep. The processing in the heat treatment apparatus 1 proceeds as the CPU of the control unit 3 executes a predetermined processing program.

  By the way, the semiconductor wafer W which is an object of the heat treatment in the heat treatment apparatus 1 is one in which impurities are implanted into the surface portion, and the activation process of the impurities implanted by the heat treatment by the heat treatment apparatus 1 can be executed. At this time, if the heating of the semiconductor wafer W is insufficient, the activation of impurities is insufficient. Then, in the surface portion of the semiconductor wafer W after the heat treatment, a portion where the activation of the impurity is sufficient, a portion having a preferable sheet resistance (Rs) or lower sheet resistance, and the activation of the impurity is insufficient. Then, there exists a tendency which exhibits a sheet resistance higher than a preferable sheet resistance.

  In general, for a heat treatment apparatus that performs heat treatment on a semiconductor wafer, the sheet resistance of the semiconductor wafer after heat treatment is used as an index for managing process performance. This sheet resistance is a parameter that can change from day to day in accordance with contamination in the chamber of the heat treatment apparatus and deterioration of various lamps and other parts due to continuous use of the heat treatment apparatus. Therefore, in order to maintain the process performance of the heat treatment apparatus, maintenance of the heat treatment apparatus is performed at a regular timing such as every week so that the sheet resistance of the semiconductor wafer after the heat treatment approaches a desirable value (target value). It ’s fine.

  Specifically, in order to realize a semiconductor wafer W having desired characteristics, a portion of the semiconductor wafer W after the heat treatment that exhibits a low sheet resistance has a reduced heat treatment temperature and a portion that exhibits a high sheet resistance. The heat treatment apparatus may be adjusted so that the heat treatment temperature is raised. By the way, a method of adjusting the level of the heat treatment temperature by adjusting the level of the energy of the light output from the halogen lamp HL can be considered, but the directivity of the light emitted from the halogen lamp is low. The portion that does not require an increase in the energy of the light is excessively heated.

  Therefore, a configuration in which a part of the light radiated to the portion exhibiting a low sheet resistance among the light radiated from the halogen heating unit 4 to the semiconductor wafer W is adjusted to be radiated to the portion exhibiting a high sheet resistance. Can be considered. That is, for example, in the surface portion of the semiconductor wafer W after being irradiated with light by the plurality of halogen lamps HL and flash light by the flash lamp FL, the actual surface is larger than the sheet resistance value in the reference in-plane distribution. The angular relationship between the one or more reflectors 4Rf and the plurality of halogen lamps HL is such that the amount of light emitted from the plurality of halogen lamps HL increases in a region having a higher sheet resistance value in the internal distribution. It only has to be changed. In this case, since a larger amount of light is irradiated to a region where the sheet resistance is higher in the surface portion of the semiconductor wafer W after the heat treatment, the semiconductor wafer W is preheated by light irradiation. The in-plane temperature distribution can be made more uniform.

  In the heat treatment apparatus 1 according to the present embodiment, an actual in-plane distribution of sheet resistance (both in-plane distribution) on the surface portion of the semiconductor wafer W after being heated by the first irradiation and the second irradiation. Say) is obtained by actual measurement. Then, the difference (also referred to as Rs difference) between the Rs in-plane distribution (also referred to as the reference in-plane distribution) and the actual in-plane distribution as a reference set in advance for the in-plane distribution of the sheet resistance on the surface portion of the semiconductor wafer W. Accordingly, the control unit 3 changes the angular relationship between the one or more reflectors 4Rf as at least a part of the reflecting unit 4R and the plurality of halogen lamps HL. As a result, in the heat treatment apparatus 1 that heats the semiconductor wafer W by irradiation with flash light, the in-plane temperature distribution of the semiconductor wafer W can be made more uniform during preheating by light irradiation.

  For example, the control unit 3 adjusts the angle of the one or more reflectors 4Rf with respect to the halogen lamp HL so that the fluctuation in the value in the in-plane distribution of the Rs difference becomes smaller according to the in-plane distribution of the Rs difference. Feedback control is performed. Here, for example, each reflector 4Rf only needs to be rotatable with respect to the halogen lamp HL by driving a motor or the like by automatic control of the control unit 3.

  The reference in-plane distribution indicates a preferable in-plane distribution (also referred to as a target Rs in-plane distribution) which is a target of the sheet resistance Rs on the surface portion of the semiconductor wafer W, and is stored in advance in the ROM or the like of the control unit 3, for example. Can be set. As the reference in-plane distribution, for example, an in-plane distribution of sheet resistance at the surface portion of the semiconductor wafer W that has been heat-treated using the heat treatment apparatus 1 at a certain time (for example, in an initial state), or a computer simulation or the like An in-plane distribution of sheet resistance obtained by calculation can be employed.

  The actual in-plane distribution is measured for the semiconductor wafer W that has been subjected to the heat treatment using the heat treatment apparatus 1, and is measured at a predetermined interval on the semiconductor wafer W by using, for example, a so-called four-terminal method. Can be obtained by

  The in-plane distribution of the Rs difference can be acquired, for example, by calculating a value difference between the reference in-plane distribution and the actual in-plane distribution for each measurement point of the semiconductor wafer W. The difference acquired at this time is, for example, the value of the sheet resistance of the distribution in the reference plane from the value of the sheet resistance in the distribution in the actual plane for each measurement point so that the positive and negative with respect to the distribution in the reference plane becomes clear Acquired by reducing. Note that the in-plane distribution of the Rs difference may be calculated, for example, in an external apparatus disposed outside the heat treatment apparatus 1. In this case, it suffices if the data of the reference in-plane distribution is stored in the external device, and, for example, each measurement value related to the actual in-plane distribution is input to the external device. An internal distribution can be calculated.

  Regarding the feedback control in the control unit 3, the amount of light irradiated to the portion showing a positive value in the in-plane distribution of the Rs difference in the semiconductor wafer W is increased, and the portion showing the negative value is irradiated. The angle of the reflector 4Rf is adjusted so that the amount of light is reduced. Specifically, for example, an aspect is assumed in which a value for the angle of the reflector 4Rf can be calculated by applying the in-plane distribution of the Rs difference to a preset calculation formula.

  Such a calculation formula can be calculated by the following method, for example. First, the heat treatment temperature of the semiconductor wafer W by the halogen heating unit 4 is intentionally varied by appropriately adjusting the angle of the reflector 4Rf using the heat treatment apparatus 1. Next, by measuring the sheet resistance at each measurement point on the surface portion of the semiconductor wafer W after the plurality of heat treatments, the relationship between the temperature and the sheet resistance and the angle and temperature of the reflector 4Rf are measured at each measurement point. A relationship is detected. A relationship between the angle of the reflector 4Rf and the sheet resistance is obtained. That is, the relationship between the angles of the plurality of reflectors 4Rf and the in-plane distribution of the sheet resistance is calculated. From the relationship between the angle of the plurality of reflectors 4Rf and the in-plane distribution of the sheet resistance, a calculation formula can be set in advance.

  If such a configuration is adopted, for example, if data relating to the in-plane distribution of the Rs difference is input in the control unit 3, values relating to the angles of the plurality of reflectors 4Rf are calculated. For example, in the control unit 3, the actual angles of the plurality of reflectors 4Rf are adjusted according to the calculated angles of the plurality of reflectors 4Rf.

  In addition to the above configuration, the heat treatment apparatus 1 prevents an excessive temperature rise in the halogen heating unit 4, the flash heating unit 5, and the chamber 6 due to thermal energy generated from the halogen lamp HL and the flash lamp FL during the heat treatment of the semiconductor wafer W. Therefore, various cooling structures are provided. For example, the wall of the chamber 6 is provided with a water-cooled tube (not shown). Further, the halogen heating unit 4 and the flash heating unit 5 have an air cooling structure in which a gas flow is formed inside to exhaust heat. 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.

  Here, a processing procedure of the semiconductor wafer W in the heat treatment apparatus 1 will be described. The semiconductor wafer W to be processed is a semiconductor substrate to which impurities (ions) are added by an ion implantation method. Activation of the impurities is performed by heat treatment (annealing) of flash light irradiation 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 air supply valve 84 is opened, and the exhaust valves 89 and 192 are opened to start supply and exhaust of air into the chamber 6. When the valve 84 is opened, nitrogen gas is supplied from the gas supply hole 81 to the heat treatment space 65. When the valve 89 is opened, the gas in the chamber 6 is exhausted from the gas exhaust hole 86. Thereby, the nitrogen gas supplied from the upper part of the heat treatment space 65 in the chamber 6 flows downward and is exhausted from the lower part of the heat treatment space 65.

  Further, when the valve 192 is opened, the gas in the chamber 6 is also exhausted from the transfer opening 66. Further, the atmosphere around the drive unit of the transfer mechanism 10 is also exhausted by an exhaust mechanism (not shown). Note that nitrogen gas is continuously supplied to the heat treatment space 65 during the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1, and the supply amount is appropriately changed according to the treatment process.

  Subsequently, the gate valve 185 is opened to open the transfer opening 66, and the semiconductor wafer W after the ion implantation is transferred into the heat treatment space 65 in the chamber 6 through the transfer opening 66 by the transfer robot outside the apparatus. . The semiconductor wafer W carried in by the carrying robot advances to a position directly above the holding unit 7 and stops. Then, when the pair of transfer arms 11 of the transfer mechanism 10 moves horizontally from the retracted position to the transfer operation position and rises, the lift pins 12 protrude from the upper surface of the susceptor 74 through the through holes 79 and the semiconductor wafer W. Receive. At this time, the lift pin 12 rises above the upper end of the support pin 77 of the susceptor 74.

  After the semiconductor wafer W is placed on the lift pins 12, the transfer robot leaves the heat treatment space 65 and the transfer opening 66 is closed by the gate valve 185. When the pair of transfer arms 11 are lowered, the semiconductor wafer W is transferred from the transfer mechanism 10 to the susceptor 74 of the holding unit 7 and held from below in a horizontal posture. At this time, the semiconductor wafer W is arranged at a position drawn by a two-dot chain line in FIG. The semiconductor wafer W is supported by point contact by a plurality of support pins 77 erected on the holding plate 75 and held by the susceptor 74. The semiconductor wafer W is supported by a plurality of support pins 77 so that the center thereof coincides with the central axis of the mounting surface 75a of the holding plate 75 (that is, at the center of the mounting surface 75a). Therefore, the semiconductor wafer W is supported by the plurality of support pins 77 at a predetermined interval with respect to the tapered surface 76 a on the inner side of the tapered surface 76 a on the inner periphery of the guide ring 76. The semiconductor wafer W is held by the susceptor 74 with the surface on which the pattern is formed and the impurities are implanted as the upper surface. A predetermined interval is formed between the back surface (main surface opposite to the front surface) of the semiconductor wafer W supported by the plurality of support pins 77 and the mounting surface 75 a of the holding plate 75. The pair of transfer arms 11 lowered to below the susceptor 74 is retracted to the retracted position, that is, inside the recess 62 by the horizontal movement mechanism 13.

  After the semiconductor wafer W is held from below in a horizontal posture by the susceptor 74 of the holding unit 7, the 40 halogen lamps HL of the halogen heating unit 4 are turned on all at once and preheating (assist heating) is started. The halogen light emitted from the halogen lamp HL passes through the lower chamber window 64 and the susceptor 74 made of quartz and is irradiated from the back surface of the semiconductor wafer W. By receiving the light from the halogen lamp HL, the semiconductor wafer W is preheated and the temperature rises. In addition, since the transfer arm 11 of the transfer mechanism 10 is retracted to the inside of the recess 62, there is no obstacle to heating by the halogen lamp HL.

  When preheating is performed by the halogen lamp HL, the temperature of the semiconductor wafer W is measured by the radiation thermometer 120. That is, the infrared thermometer 120 receives infrared light emitted from the back surface of the semiconductor wafer W held by the susceptor 74 through the opening 78, and measures the temperature of the wafer being heated. The measured temperature of the semiconductor wafer W is transmitted to the control unit 3. The controller 3 monitors whether or not the temperature of the semiconductor wafer W that is heated by irradiation with light from the halogen lamp HL has reached a predetermined preheating temperature T1. The preheating temperature T1 is set to about 200 ° C. to 800 ° C., preferably about 350 ° C. to 600 ° C. (in this embodiment, 600 ° C.) at which impurities added to the semiconductor wafer W are not likely to diffuse due to heat.

  After the temperature of the semiconductor wafer W reaches the preheating temperature T1, the control unit 3 maintains the semiconductor wafer W at the preheating temperature T1 for a while. Specifically, when the temperature of the semiconductor wafer W measured by the radiation thermometer 120 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 substantially spare. The heating temperature is maintained at T1.

  By performing such preheating by the halogen lamp HL, the entire semiconductor wafer W is uniformly heated to the preheating temperature T1. In the preliminary heating stage with the halogen lamp HL, the temperature of the peripheral edge of the semiconductor wafer W where heat dissipation is more likely to occur tends to be lower than that in the central area, but the arrangement density of the halogen lamps HL in the halogen heating section 4 is The region facing the peripheral portion is higher than the region facing the central portion of the semiconductor wafer W. Furthermore, since the inner peripheral surface of the reflection ring 69 attached to the chamber side portion 61 is a mirror surface, the amount of light reflected toward the peripheral edge of the semiconductor wafer W by the inner peripheral surface of the reflection ring 69 increases. The in-plane temperature distribution of the semiconductor wafer W in the preheating stage can be made more uniform. If the angular relationship between the one or more reflectors 4Rf as at least a part of the reflecting portion 4R and the plurality of halogen lamps HL is changed by the control unit 3 according to the in-plane distribution of the Rs difference, the preliminary heating is performed. The in-plane temperature distribution of the semiconductor wafer W can be made more uniform.

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

  Since the flash heating is performed by irradiation with flash light (flash light) from the flash lamp FL, the surface temperature of the semiconductor wafer W can be increased in a short time. That is, the flash light emitted from the flash lamp FL is converted into a light pulse in which the electrostatic energy stored in advance in the condenser is extremely short, and the irradiation time is about 0.1 milliseconds or more and about 100 milliseconds or less. It is a very short and strong flash. Then, the surface temperature of the semiconductor wafer W subjected to flash heating by flash light irradiation from the flash lamp FL instantaneously rises to a processing temperature T2 of 1000 ° C. or higher, and the impurities implanted into the semiconductor wafer W are activated. After being converted, the surface temperature rapidly decreases. As described above, in the heat treatment apparatus 1, the surface temperature of the semiconductor wafer W can be raised and lowered in a very short time, so that the impurities are activated while suppressing diffusion of the impurities injected into the semiconductor wafer W due to heat. Can do. Since the time required for the activation of impurities is extremely short compared with the time required for the thermal diffusion, the activation is possible even in a short time in which no diffusion occurs in the order of 0.1 to 100 milliseconds. Complete.

  By the way, the surface temperature of the semiconductor wafer W instantaneously rises to the processing temperature T2 of 1000 ° C. or more by the irradiation of the flash light, while the back surface temperature at that moment does not increase so much from the preheating temperature T1. That is, a temperature difference is instantaneously generated between the front surface and the back surface of the semiconductor wafer W. As a result, rapid thermal expansion occurs only on the surface of the semiconductor wafer W, and almost no thermal expansion occurs on the back surface, so that the semiconductor wafer W is warped instantaneously so that the surface is convex. Due to the occurrence of an instantaneous warp with such a convex surface, the semiconductor wafer W jumps from the susceptor 74 and floats.

  The semiconductor wafer W jumping and floating from the susceptor 74 falls toward the susceptor 74 immediately after that. At this time, the thin semiconductor wafer W jumps upward along the vertical direction and does not necessarily drop downward in the vertical direction, but rather falls with the horizontal position shifted. As a result, the outer peripheral end of the semiconductor wafer W collides with the tapered surface 76 a of the guide ring 76.

  Here, a surface of the guide ring 76 on the side of the semiconductor wafer W is a tapered surface 76 a that is tapered upward from the holding plate 75. For this reason, when the outer peripheral end of the disk-shaped semiconductor wafer W collides with the guide ring 76, the contact area at the time of the collision becomes larger than the collision with the guide pin by point contact, and the impact is alleviated. As a result, it is possible to prevent cracking of the semiconductor wafer W during irradiation with flash light and to prevent the guide ring 76 from being damaged. In particular, when the outer peripheral edge of the semiconductor wafer W collides with the tapered surface 76a, the kinetic energy is dispersed and the impact is further relaxed, and the cracking of the semiconductor wafer W can be prevented more reliably than when colliding with the horizontal surface. it can.

  Further, when the outer peripheral edge of the semiconductor wafer W collides with the tapered surface 76a, the outer peripheral edge slides obliquely downward along the tapered surface 76a, and the horizontal position of the semiconductor wafer W is the position before the flash light irradiation (mounting surface). 75a (center of 75a). As a result, the dropped semiconductor wafer W is supported by the plurality of support pins 77.

  After the semiconductor wafer W jumped by the flash light irradiation falls and is supported by the plurality of support pins 77, the halogen lamp HL is turned off after a predetermined time has elapsed. Thereby, the temperature of the semiconductor wafer W is rapidly lowered from the preheating temperature T1. The temperature of the semiconductor wafer W during the temperature drop is also measured by the radiation thermometer 120, and the measurement result is transmitted to the control unit 3. The controller 3 monitors whether or not the temperature of the semiconductor wafer W has dropped to a predetermined temperature from the measurement result. Then, after the temperature of the semiconductor wafer W is lowered to a predetermined temperature or lower, the pair of transfer arms 11 of the transfer mechanism 10 is moved horizontally from the retracted position to the transfer operation position again and lifted, whereby the lift pins 12 are moved to the susceptor. The semiconductor wafer W protruding from the upper surface of 74 and subjected to the heat treatment is received from the susceptor 74. Subsequently, the transfer opening 66 closed by the gate valve 185 is opened, and the semiconductor wafer W placed on the lift pins 12 is unloaded by the transfer robot outside the apparatus, and the heat treatment of the semiconductor wafer W in the heat treatment apparatus 1 is performed. Is completed.

  Although the horizontal position of the semiconductor wafer W may be shifted from the position before the flash light irradiation by jumping and dropping at the time of flash light irradiation, the semiconductor wafer W is supported by a plurality of support pins 77. If it is in a state, it is possible to receive the semiconductor wafer W by the lift pins 12 of the transfer mechanism 10 and carry it out by the transfer robot.

  Next, the procedure in the adjustment method of the heat treatment apparatus 1 performed periodically in the heat treatment apparatus 1 will be described. FIG. 11 and FIG. 12 are flowcharts showing the procedure in the method for adjusting the heat treatment apparatus 1. Here, as shown in FIG. 11, the procedures of steps ST1 to ST4 are executed in time sequence. FIG. 12 is a flowchart according to an example of the process of step ST4 of FIG.

  First, in step ST1, the semiconductor wafer W to which impurities (ions) are added is held by the holding unit 7 in the heat treatment apparatus 1 by an ion implantation method. Here, the semiconductor wafer W is carried into the chamber 6 and placed on the plurality of support pins 77 of the susceptor 74.

  Next, in step ST2, preliminary heating is performed on the semiconductor wafer W held by the holding unit 7 by light irradiation (first irradiation) from a plurality of halogen lamps HL, and the preliminary After the start of heating, the semiconductor wafer W is heated by irradiation with flash light (second irradiation) by a plurality of flash lamps FL. Thereby, the activation process of the impurities in the semiconductor wafer W is executed. Here, the semiconductor wafer W is carried out of the chamber 6 after the heat treatment.

  Next, in step ST3, the sheet resistance Rs in the surface portion of the semiconductor wafer W after the first irradiation and the second irradiation in step ST2 are measured, whereby the sheet resistance in the surface portion of the semiconductor wafer W is measured. An in-plane distribution (real in-plane distribution) of Rs is acquired. Here, for example, the sheet resistance Rs is detected at a predetermined interval such as one to several millimeters.

  Next, in step ST4, one or more reflectors 4Rf as a part of at least a part of the reflecting portion 4R and a plurality of reflectors 4Rf according to the relationship between the actual in-plane distribution acquired in step ST3 and the preset reference in-plane distribution. The angular relationship with the halogen lamp HL is changed.

  In step ST4, as shown in FIG. 12, for example, in step ST41, a difference between the actual in-plane distribution acquired in step ST3 and a preset reference in-plane distribution is calculated. Here, for example, by calculating the difference in value between the reference in-plane distribution and the actual in-plane distribution for each measurement point of the semiconductor wafer W, the in-plane distribution of the Rs difference can be acquired. Specifically, the in-plane distribution of Rs difference is obtained by subtracting the value of the sheet resistance of the reference in-plane distribution from the value of the sheet resistance of the in-plane distribution for each measurement point. In step ST42, the angular relationship between the one or more reflectors 4Rf as at least a part of the reflecting portion 4R and the plurality of halogen lamps HL is changed according to the difference calculated in step ST41. Here, for example, by applying the in-plane distribution of the Rs difference to a preset calculation formula, values for the angles of the plurality of reflectors 4Rf are calculated, and according to the values, the values of the plurality of reflectors 4Rf are calculated. The angle is changed.

  As described above, in the heat treatment apparatus 1 according to an embodiment, the angular relationship between the one or more reflectors 4Rf as at least a part of the reflecting portion 4R and the halogen lamp HL can be changed. Thereby, the direction in which the light from at least some of the halogen lamps HL is reflected can be changed. As a result, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during heating by light irradiation in the heat treatment apparatus 1.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the gist of the present invention.

  For example, in the heat treatment apparatus 1 of the above-described embodiment, the reflecting portion 4R provided with the reflector 4Rf for each halogen lamp HL is employed, but is not limited thereto. For example, instead of the reflecting portion 4R, a reflecting portion 4RA in which one reflector 4RfA is provided for each of the plurality of halogen lamps HL may be employed. Here, a specific example of the reflection unit 4RA according to a modification will be described.

  FIG. 13 is a cross-sectional view illustrating the arrangement of the reflector 4RA according to a modification. FIG. 14 is a diagram illustrating a state in which the angle of the reflector 4RfA according to the modification is changed. In FIG. 13 and FIG. 14, the traveling direction of light emitted from each halogen lamp HL is indicated by an arrow drawn by a linear thin line. As shown in FIG. 13, in the reflector 4RA according to this modification, one reflector 4RfA is provided for every two halogen lamps HL. FIG. 13 shows a configuration in which three reflectors 4RfA1 to 4RfA3 are provided for the six halogen lamps HL1 to HL6. FIG. 14 shows a state in which the angular relationship between the three reflectors 4RfA1 to 4RfA3 and the three halogen lamps HL1 to HL3 as a part of the reflector 4RA is changed. Here, the direction in which the reflector 4RfA rotates is indicated by an arrow.

  Note that a reflecting portion provided with one reflector may be employed for all halogen lamps HL. According to such a configuration, when the sheet resistance Rs monotonously changes in one direction of the semiconductor wafer W, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during heating by light irradiation. However, if a reflector is provided for each of a smaller number of halogen lamps HL, the distribution of the amount of light irradiated onto the semiconductor wafer W can be finely adjusted. In addition, the in-plane temperature distribution of the semiconductor wafer W can be further uniformized during heating by light irradiation.

  In the above embodiment, the number of halogen lamps HL in the halogen heating unit 4 is 40. However, the number is not limited to this, and the number of halogen lamps HL can be set to an arbitrary number.

  Moreover, in the said one Embodiment, although the halogen heating part 4 as an irradiation part has several rod-shaped halogen lamps HL, it is not restricted to this. For example, an irradiation unit having a plurality of point light sources or a plurality of surface light sources may be employed. That is, an irradiation unit having a plurality of lamps may be employed.

  Moreover, in the said one Embodiment, although each reflector was rotatable with respect to the halogen lamp HL by the drive of the motor by the automatic control of the control part 3, etc., it is not restricted to this. For example, a configuration in which the angle of each reflector can be changed by a manual screw or screwdriver operation may be employed.

  Further, in the above-described embodiment, one or more reflectors 4Rf as at least a part of the reflector 4R and a plurality of halogens are controlled by the controller 3 according to the difference (Rs difference) between the reference in-plane distribution and the actual in-plane distribution. Although the angular relationship with the lamp HL has been changed, the present invention is not limited to this. For example, according to the in-plane distribution of values other than the Rs difference obtained based on the actual in-plane distribution and the reference in-plane distribution, the control unit 3 and one or more reflectors 4Rf as at least a part of the reflecting unit 4R The angular relationship with the halogen lamp HL may be changed. That is, according to the relationship between the actual in-plane distribution and the reference in-plane distribution, the control unit 3 can change the angular relationship between the one or more reflectors 4Rf as at least a part of the reflecting unit 4R and the plurality of halogen lamps HL. . Even if such a configuration is adopted, the in-plane temperature distribution of the semiconductor wafer W can be more appropriately uniformed during the preheating by the light irradiation in the heat treatment apparatus 1 that heats the semiconductor wafer W by the flash light irradiation. . As the in-plane distribution of values other than the Rs difference obtained based on the actual in-plane distribution and the reference in-plane distribution, for example, the sheet resistance value in the in-plane distribution for each measurement point is set in the reference in-plane distribution. An in-plane distribution of values obtained by dividing by the value of sheet resistance can be mentioned.

  However, for example, in the surface portion of the semiconductor wafer W after being irradiated with light from the plurality of halogen lamps HL and flash light from the flash lamp FL, the actual surface is larger than the sheet resistance value in the in-plane distribution. The angular relationship between the one or more reflectors 4Rf and the plurality of halogen lamps HL is such that the amount of light emitted from the plurality of halogen lamps HL increases in a region having a higher sheet resistance value in the internal distribution. It only has to be changed. At this time, a larger amount of light is irradiated to the region where the sheet resistance becomes higher in the surface portion of the semiconductor wafer W after the heat treatment. As a result, the in-plane temperature distribution of the semiconductor wafer W can be made more uniform during preheating by light irradiation.

  Moreover, in the said one Embodiment, although the heat processing apparatus 1 had the flash heating part 5, it is not restricted to this. For example, an aspect in which the heat treatment apparatus 1 includes the halogen heating unit 4 without including the flash heating unit 5 may be employed. At this time, for example, the halogen heating unit 4 as the irradiation unit does not preliminarily heat the semiconductor wafer W, but can mainly heat the semiconductor wafer W by light irradiation. Even with such a configuration, the in-plane temperature distribution of the semiconductor wafer W can be made uniform during heating by irradiation with light from the halogen heating unit 4. Examples of such a heat treatment apparatus include an RTP (Rapid Thermal Process) apparatus using a halogen lamp.

  The substrate to be processed by the heat treatment apparatus according to the present invention is not limited to the semiconductor wafer W, and may be a glass substrate or a solar cell substrate used for a flat panel display such as a liquid crystal display device. The technique according to the present invention can also be applied to bonding of metal and silicon, crystallization of polysilicon, or the like. However, if the semiconductor wafer W into which impurities are introduced into the surface portion is to be processed, it is possible to change the angle of the reflector according to the in-plane distribution of the sheet resistance, and the in-plane of the semiconductor wafer W during heating by light irradiation A uniform temperature distribution can be easily achieved.

  Needless to say, all or a part of each of the above-described embodiment and various modifications can be combined as appropriate within a consistent range.

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 3 Control part 4 Halogen heating part 4R, 4RA Reflection part 4Rf, 4Rf1-4Rf6, 4RfA, 4RfA1-4RfA3 Reflector 5 Flash heating part 7 Holding part FL Xenon flash lamp (flash lamp)
HL, HL1-HL6 Halogen lamp Rs Sheet resistance W Semiconductor wafer

Claims (8)

A heat treatment apparatus for heating a substrate by irradiating the substrate with light,
A holding unit for holding the substrate;
An irradiation unit that has a plurality of lamps and heats the substrate by irradiating the substrate with light emitted from the plurality of lamps;
With
The irradiation unit is
A reflection unit for reflecting the light emitted from the plurality of said substrate of the lamp are arranged on the opposite side and the plurality of lamps to the substrate,
A plurality of first lamps that are included in the plurality of lamps and that heat the substrate held by the holding unit by a first irradiation of light;
A second lamp that is not included in the plurality of lamps and that heats the substrate held by the holding unit by a second irradiation of light ;
The first irradiation is:
Started prior to the second irradiation,
The plurality of first lamps are
Preliminarily heating the substrate held by the holding unit by the first irradiation before heating by the second irradiation;
The reflective portion is
Each of the first lamps of the plurality of first lamps includes a reflector that reflects light emitted from the first lamp toward the substrate, or two of the plurality of first lamps A reflector for reflecting light emitted from the two or more first lamps toward the substrate for each first lamp group including one or more first lamps;
Whether the direction in which the light from the first lamp is reflected by the reflector is changed by changing the angular relationship between the reflector and the first lamp for each of the first lamps. Alternatively, the angle relationship between the reflector and the two or more first lamps is changed for each of the first lamp groups, so that the light from the two or more first lamps is reflected by the reflector. Is a heat treatment apparatus characterized by being changed . The heat treatment apparatus according to claim 1 ,
The second lamp is
A heat treatment apparatus comprising: a flash lamp that heats the substrate held by the holding portion by the second irradiation with flash light. The heat treatment apparatus according to claim 2 ,
The substrate is
It is a semiconductor substrate in which impurities are implanted in the surface portion,
The heat treatment apparatus is
About the actual in-plane distribution of the sheet resistance at the surface portion of the semiconductor substrate after being heated by the first irradiation and the second irradiation, and the in-plane distribution of the sheet resistance at the surface portion of the semiconductor substrate Depending on the relationship with the reference in-plane distribution that is set in advance, the angular relationship between the reflector and the first lamp is changed for each of the first lamps, or the first lamp is changed. A controller that changes the angular relationship between the reflector and the two or more first lamps for each group ;
A heat treatment apparatus further comprising: The heat treatment apparatus according to claim 3 ,
The control unit is
The sheet resistance value in the actual in-plane distribution is larger than the sheet resistance value in the reference in-plane distribution of the surface portion of the semiconductor substrate after the first irradiation and the second irradiation are performed. The angle relationship between the reflector and the one first lamp is changed for each one first lamp so that the amount of light emitted from the irradiating unit increases with respect to the higher region , Alternatively , the heat treatment apparatus is characterized in that the angular relationship between the reflector and the two or more first lamps is changed for each of the first lamp groups . The heat treatment apparatus according to claim 4 ,
The control unit is
Depending on the difference between the actual in-plane distribution and the reference in-plane distribution , the angular relationship between the reflector and the one first lamp is changed for each one first lamp, or the first A heat treatment apparatus that changes an angular relationship between the reflector and the two or more first lamps for each lamp group . An adjustment method of a heat treatment apparatus for heating a semiconductor substrate by irradiating light onto the semiconductor substrate into which impurities are implanted,
(a) holding the semiconductor substrate in a holder in the heat treatment apparatus;
(b) Preliminary heating is performed on the substrate held by the holding unit by first irradiation with light from a plurality of first lamps, and the semiconductor substrate is started after the preliminary heating is started. Heating with the second irradiation of flash light by the second lamp;
(c) The sheet resistance at the surface portion of the semiconductor substrate is measured by measuring the sheet resistance at the surface portion of the semiconductor substrate after the first irradiation and the second irradiation are performed in the step (b). Obtaining an actual in-plane distribution;
(d) According to the relationship between the actual in-plane distribution acquired in step (c) and a reference in-plane distribution that is a preset reference for the in-plane distribution of sheet resistance at the surface portion of the semiconductor substrate. In addition, for each first lamp of the plurality of first lamps, an angular relationship between a reflector that reflects light emitted from the first lamp toward the semiconductor substrate and the one first lamp. Or for each first lamp group including two or more first lamps of the plurality of first lamps, the light emitted from the two or more first lamps is directed toward the semiconductor substrate. Changing the angular relationship between the reflecting reflector and the two or more first lamps;
A method for adjusting a heat treatment apparatus, comprising: It is the adjustment method of the heat processing apparatus of Claim 6 , Comprising:
In step (d),
The sheet resistance value in the actual in-plane distribution is larger than the sheet resistance value in the reference in-plane distribution of the surface portion of the semiconductor substrate after the first irradiation and the second irradiation are performed. The one first lamp for each first lamp of the plurality of first lamps so that the amount of light emitted from the plurality of first lamps increases with respect to the higher region. The angle relationship between the reflector that reflects the light emitted from the semiconductor substrate toward the semiconductor substrate and the one first lamp is changed, or two or more first lamps of the plurality of first lamps are included. A heat treatment characterized by changing an angular relationship between a reflector that reflects light emitted from the two or more first lamps toward the semiconductor substrate and the two or more first lamps for each lamp group. Device adjustment method. A method for adjusting a heat treatment apparatus according to claim 7 ,
Step (d)
(d1) calculating the difference between the actual in-plane distribution acquired in step (c) and the reference in-plane distribution;
(d2) Depending on the difference calculated in the step (d1), for each one of the plurality of first lamps, light emitted from the first lamp is supplied to the semiconductor substrate. For each first lamp group that includes two or more first lamps of the plurality of first lamps, the angular relationship between the reflector that reflects toward the first lamp and the first lamp is changed. Changing the angular relationship between the reflector that reflects the light emitted from the first lamp toward the semiconductor substrate and the two or more first lamps ;
The adjustment method of the heat processing apparatus characterized by including.

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