JP4502220B2 - Heat treatment equipment - Google Patents

Description

  The present invention relates to a heat treatment apparatus for performing a process involving heating on a substrate.

  As the demand for microfabrication of devices such as semiconductors increases, a rapid heating process (hereinafter referred to as “RTP”) is important as one of the heating processes of a semiconductor substrate (hereinafter referred to as “substrate”). Playing a role. In RTP, a lamp is mainly used as a heating source, and the substrate is heated to a predetermined temperature (for example, 1100 ° C.) in a second order while keeping the processing chamber in a predetermined gas atmosphere (for example, 1100 ° C.) for a certain time (for example, After being maintained at that temperature for several tens of seconds (holding step), rapid cooling is performed by turning off the lamp.

  With RTP, processing that was difficult to achieve with long-term heat treatment in a conventional electric furnace, such as prevention of re-diffusion of impurities due to heat in the junction layer of transistors built into the substrate, and thinning of insulating films such as oxide films, etc. Done.

  In a heat treatment apparatus that performs RTP, an auxiliary ring that supports a substrate by being in contact with an outer edge portion of the substrate is provided. The auxiliary ring prevents the light from the lamp from entering a thermometer disposed on the back side of the substrate in order to measure the temperature of the substrate in the RTP, and is heated integrally with the substrate so that the surface of the substrate is Improve temperature uniformity.

  However, since the combined thickness of the portion where the substrate and the auxiliary ring are in contact with each other is larger than the portion where only the substrate is present, the heat capacity per unit area is increased in a pseudo manner at the outer edge portion of the substrate. It becomes difficult to maintain the temperature uniformity of the substrate in both the temperature raising step and the holding step. As a result, for example, it becomes difficult to suppress variations in film thickness when forming an oxide film or the like within a range that will be required more strictly in the future. Hereinafter, an example of oxide film generation by a conventional heat treatment apparatus will be described.

  FIG. 1 is a diagram showing temporal changes in substrate temperature in RTP. The horizontal axis represents time, and the vertical axis represents the substrate temperature. The process from time t1 to t2 in FIG. 1 is a temperature raising process for raising the substrate temperature, and the process from time t2 to t3 is a holding process for keeping the substrate temperature at the target temperature A. FIG. 2 shows the relationship between the position on the substrate and the thickness of the oxide film when such RTP is performed using a conventional heat treatment apparatus. The horizontal axis indicates the distance from the center of the substrate, and the vertical axis indicates the average thickness of the oxide film with respect to the distance.

  As shown in FIG. 2, the film thickness is stable on the inner side (center side of the substrate) than the vicinity of the distance R1, but the film thickness increases rapidly as the distance R2 corresponding to the outer edge of the substrate is approached. This is considered to be because the temperature of the auxiliary ring becomes higher than the substrate temperature in the holding step, and the temperature of the outer edge of the substrate becomes higher than the inner portion due to the heat conducted from the auxiliary ring. .

  The present invention has been made in view of the above problems, and an object thereof is to improve the uniformity of the substrate temperature in a heat treatment apparatus using a lamp.

The invention according to claim 1 is a heat treatment apparatus that performs a process involving heating by irradiating a substrate with light, and supports a lamp group that irradiates the substrate with light and an outer edge portion of the substrate in contact with each other from below. An auxiliary ring having an annular support portion and extending outward from the outer edge portion; and an annular buffer ring for supporting the auxiliary ring from the outer side, wherein the outer edge portion of the substrate to be supported and the support portion are in contact with each other. The support width in contact is 1.0 millimeter or more, the thickness of the support portion is 0.3 millimeter or more, and the value expressed in square millimeters by multiplying the support width and the thickness of the support portion, 0.4 or more, less than the value expressed in millimeters by doubling the thickness of the substrate, the buffer ring supports the outer edge portion of the auxiliary ring from below by annular surface contact, Lamp groups are independent of each other It is divided into a plurality of small groups to which electric power is supplied Te, toward mainly the auxiliary ring to the plurality of small groups include small groups of performing light irradiation.

  Invention of Claim 2 is the heat processing apparatus of Claim 1, Comprising: The electric power supplied to the said small group which irradiates light mainly toward the said auxiliary | assistant ring in a temperature rising process from other things Is also raised.

  Invention of Claim 3 is the heat processing apparatus of Claim 1 or 2, Comprising: The electric power to these several small groups according to the measurement result of several radiation thermometers and these several radiation thermometers And a lamp control unit for controlling supply.

  Invention of Claim 4 is the heat processing apparatus in any one of Claim 1 thru | or 3, Comprising: The said value which multiplied the said support width and the said thickness of the said support part is 1.5 or less.

  The invention according to claim 5 is the heat treatment apparatus according to any one of claims 1 to 4, wherein the support width is 3 millimeters or less.

  A sixth aspect of the present invention is the heat treatment apparatus according to any one of the first to fifth aspects, wherein the support portion has a thickness of 0.5 mm or less.

  The invention according to claim 7 is the heat treatment apparatus according to any one of claims 1 to 6, wherein the auxiliary ring is formed of silicon carbide.

  The invention according to claim 8 is the heat treatment apparatus according to any one of claims 1 to 7, wherein the auxiliary ring has a cylindrical surface facing the outer peripheral surface of the substrate.

  According to the present invention, in the heat treatment apparatus using a lamp, the uniformity of the temperature of the substrate to be heated can be improved.

  3 and 4 are longitudinal sectional views showing the configuration of the heat treatment apparatus 1 according to one embodiment of the present invention. The cut surface in FIG. 3 and the cut surface in FIG. It intersects perpendicularly with the central axis 1a facing. In FIGS. 3 and 4, description of parallel oblique lines with respect to the cross section of the details is omitted.

  The heat treatment apparatus 1 includes a main body 11 that is an apparatus main body, a lid 12 that covers an upper portion of the main body 11, and a reflection plate 13 that is disposed on a central bottom surface of the main body 11, thereby forming an internal space. The The internal space is partitioned up and down by a chamber window 21 made of quartz, and the substrate 9 is supported by a support ring group 30 described later in the lower processing space 10. The chamber window 21 and the main body 11 are sealed with an O-ring (not shown), and the inner surface of the main body 11 is a cylindrical surface.

  A plurality of gas introduction ports 111 and exhaust ports 112 are formed on the side wall of the main body 11, and the gas in the processing space 10 is (forced) exhausted from the exhaust ports 112, or the substrate 9 is connected via the gas introduction ports 111. Gas replacement in the processing space 10 is performed by introducing a gas (for example, nitrogen, oxygen) according to the type of processing performed on the processing space 10. A quartz shower plate 22 having a large number of holes is provided between the substrate 9 and the chamber window 21, and the gas introduced from the gas introduction port 111 passes through the shower plate 22 to the upper surface of the substrate 9. Evenly applied. The gas used for the processing is guided from the lower side of the processing space 10 to the exhaust port 112.

  As shown in FIGS. 3 and 4, the support ring group 30 is supported by a cylindrical member 33 having a central axis 1 a as a center, and a coupling member 331 is attached to the lower end of the cylindrical member 33. A coupling member 332 that faces the coupling member 331 is provided below the main body 11, and the coupling member 331 and the coupling member 332 constitute a magnetic coupling mechanism. The coupling member 332 is rotated around the central axis 1a by a motor 333 shown in FIG. Thereby, the coupling member 331 inside the main body 11 is rotated by a magnetic action, and the substrate 9 and the support ring group 30 are rotated around the central axis 1a.

  The lower surface of the lid 12 is a reflecting surface (hereinafter referred to as “reflector”) 121 that faces the upper surface of the substrate 9, and the upper portion of the rod-like shape so that each of them faces the X direction in FIG. 3 along the reflector 121. A lamp group 41 is arranged. Of the light from the upper lamp group 41, the light emitted upward is reflected by the reflector 121 and irradiated onto the substrate 9.

  Below the upper lamp group 41 (that is, between the upper lamp group 41 and the substrate 9), rod-shaped lower lamp groups 42 are arranged so as to face each other in the Y direction. That is, the upper lamp group 41 and the lower lamp group 42 are attached to the lid 12 so as to be orthogonal to each other.

  Each of the upper lamp group 41 and the lower lamp group 42 is divided into small groups according to the distance from the central axis 1a. 4, reference numerals 411, 412, 413, and 414 are given to the lamps of the grouped upper lamp group 41 from the central axis 1a side, and in FIG. 3, the central axis 1a is added to the lamps of the grouped lower lamp group 42. Reference numerals 421, 422, 423, and 424 are attached from the side.

  FIG. 5 is a block diagram showing a connection relationship between the lamps divided into small groups and the lamp control unit 6 that supplies power to the lamps (even a plurality of lamps are shown as one block). . As shown in FIG. 5, each group (the lamps 411 to 414 of the upper lamp group 41 and the lamps 421 to 424 of the lower lamp group 42) are individually connected to the lamp control unit 6 and supplied with power independently of each other. Is done. Thereby, the intensity distribution of the light irradiated on the upper surface of the substrate 9 is controlled.

  6 is a view showing the inside from the cylindrical member 33 when viewed from the position of the arrow AA in FIG. 4, and FIG. 7 is an enlarged cross-sectional view showing how the substrate 9 is supported by the support ring group 30. is there.

  As shown in FIGS. 6 and 7, the support ring group 30 includes an annular auxiliary ring 31 on which the substrate 9 is placed and an annular buffer ring 32 that supports the auxiliary ring 31 from the outside. Both the auxiliary ring 31 and the buffer ring 32 are formed of silicon carbide (SiC) having a specific heat close to that of the substrate 9. The auxiliary ring 31 has an annular support portion 311 that protrudes toward the central axis 1 a on the inner peripheral surface 310, and the substrate 9 transported into the processing space 10 by the external transport mechanism is the outer edge portion 91 of the substrate 9. The support portion 311 is supported by contacting from below. In a state where the substrate 9 is placed on the auxiliary ring 31, the outer peripheral surface 90 of the substrate 9 and the inner peripheral surface 310 of the auxiliary ring 31 face each other so that the auxiliary ring 31 spreads outward from the outer edge portion 91 of the substrate 9. Located in. In the following description, as shown in FIG. 7, the thickness of the substrate 9 is called the substrate thickness Tw, the thickness of the support portion 311 is called the support portion thickness T, and the width where the substrate 9 and the support portion 311 overlap is called the support width W. .

  The auxiliary ring 31 is supported from the outside by a concentric annular buffer ring 32, and the buffer ring 32 is supported by the aforementioned cylindrical member 33. As shown in FIG. 7, the engaging portion 391 between the auxiliary ring 31 and the buffer ring 32 and the engaging portion 392 between the buffer ring 32 and the cylindrical member 33 have gaps (plays), respectively. Even if the auxiliary ring 31 and the buffer ring 32 expand, cracking due to excessive stress is prevented.

  As shown in FIGS. 4 and 6, below the substrate 9, a plurality of radiation thermometers 51 to 53 are attached from the central axis 1 a to the outside. The radiation thermometers 51 to 53 measure the temperature of the substrate 9 by receiving infrared light from the substrate 9 through the window member 50 provided on the reflecting plate 13. Since the substrate 9 placed on the support ring group 30 rotates, the temperature of the substrate 9 corresponding to the distance from the central axis 1a is measured by the plurality of radiation thermometers 51 to 53. At that time, infrared rays from the lamp groups 41 and 42 are prevented from entering the radiation thermometers 51 to 53 by the substrate 9, the support ring group 30 and the cylindrical member 33, and accurate temperature measurement is performed by the radiation thermometers 51 to 53. Done.

  When processing involving heating is performed on the substrate 9, for example, power supply to the lamps 411 and 421 is controlled according to the measurement result of the radiation thermometer 51, and similarly, the measurement results of the radiation thermometers 52 and 53 are controlled. Accordingly, power supply to the lamps 412 and 422 and the lamps 413 and 423 is controlled. Further, the lamps 414 and 424 that mainly emit infrared rays toward the auxiliary ring 31 are supplied with power according to a predetermined profile. At this time, the substrate 9 and the support ring group 30 are rotated by a rotation mechanism including a motor 333 and a coupling mechanism, and heating of the substrate 9 is controlled so that the temperature of the substrate 9 is as uniform as possible.

  FIG. 8 shows that when the oxide film is generated by RTP in the heat treatment apparatus 1, when the support thickness T and the support width W shown in FIG. It is a figure which shows the relationship between the film thickness difference D (refer FIG. 2), and the product (TxW) of the support part thickness T and the support width W.

  In the measurement, a substrate having a diameter of 200 mm and a substrate thickness Tw of 0.725 mm is rapidly heated to a target temperature of 1100 ° C. at about 100 ° C./s, and then the target temperature is maintained for 60 seconds. Further, in order to obtain the film thickness difference D, the film thickness is measured at a position of 2 mm (corresponding to the position of distance R2 in FIG. 2) and a position of 10 mm (corresponding to the position of distance R1) from the outer edge of the substrate. Yes. It has been confirmed that the film thickness is substantially constant inside the position 10 mm from the outer edge of the substrate, and the average film thickness is about 11 nm.

FIG. 8 shows that there is a proportional relationship indicated by a straight line Z between the film thickness difference D and (T × W). Here, if the allowable film thickness variation is ± 1%, the allowable film thickness difference D is about 0.22 nm (2% of the average film thickness of 11 nm). Therefore, if (T × W) is about 1.5 mm ² or less by the straight line Z, it can be said that the variation in film thickness can be ± 1% or less. Here, considering that the smaller the substrate thickness Tw is, the variation in the film thickness is affected by the support portion thickness T and the support width W, and that the substrate 9 having the substrate thickness Tw of 0.725 mm was used in the measurement. If (T × W) is less than or equal to about twice the substrate thickness Tw, it is estimated that the variation in film thickness can be within ± 1% of the average film thickness. That is, the temperature uniformity of the substrate 9 can be improved by satisfying the relationship represented by ((T × W) ≦ (Tw × 2)).

  When the RTP is actually performed by the heat treatment apparatus 1, in the temperature rising step (from time t1 to time t2) in FIG. 1, at the portion where the substrate 9 and the auxiliary ring 31 overlap (that is, the outer edge portion of the substrate), Since the heat capacity per unit area becomes larger than that, the temperature rise is delayed. Therefore, in order to sufficiently heat the auxiliary ring 31, the power supplied to the lamps 414 and 424 is set higher than the other lamps.

  However, in such a setting, the temperature of the auxiliary ring 31 becomes higher than the temperature of the substrate 9 in the holding step (from time t2 to t3), and heat is transmitted from the auxiliary ring 31 so that the outer edge portion 91 of the substrate is hotter than other portions. End up. In the heat treatment apparatus 1, by limiting the shape of the portion where the substrate 9 and the auxiliary ring 31 overlap (the shape indicated by the support portion thickness T and the support width W) by the substrate thickness Tw, the substrate outer edge portion and the substrate center in the holding step The temperature difference from the side region is suppressed. That is, the temperature uniformity of the substrate is improved by restricting the heat transfer path from the auxiliary ring 31 to the substrate 9.

In addition, when forming a normal film thickness (about 10 nm) from FIG. 8, it can be said that (T × W) is preferably 1.5 mm ² or less, but this condition is from the measurement range shown in Table 1. In consideration of the guidance, it is preferable that the support portion thickness T is 0.5 mm or less and the support width W is 3 mm or less. In terms of obtaining a reliable measurement result, (T × W) is more preferably 1.2 mm ² or less, and support portion thickness T is more preferably 0.4 mm or less. It can be said.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made.

  In the above embodiment, the generation of the oxide film on the substrate 9 has been described as an example. However, a process involving heating other than the generation of the oxide film may be performed by the heat treatment apparatus 1. Further, the substrate 9 may have various sizes and thicknesses.

  Further, the shape of the auxiliary ring 31 is not limited to the above embodiment, and for example, a simple plate-like ring having no inner peripheral surface 310 (that is, the support portion thickness is the thickness of the auxiliary ring 31). Alternatively, an annular protrusion having a surface facing the outer peripheral surface of the substrate 9 may be provided on the upper surface of a simple plate-shaped annular ring.

  Although the substrate 9 rotates in the heat treatment apparatus 1, the substrate 9 only needs to be rotated as necessary.

  The lamps that irradiate the substrate 9 are not necessarily provided so that the upper lamp group 41 and the lower lamp group 42 are orthogonal to each other, and may be either the upper lamp group 41 or the lower lamp group 42. Further, the lamp light may be irradiated from the upper surface and the lower surface of the substrate 9.

It is a figure which shows the relationship between the temperature of a board | substrate, and time. It is a figure which shows the relationship between the distance from the center of a board | substrate, and the film thickness of an oxide film. It is a longitudinal cross-sectional view of the heat processing apparatus. It is a longitudinal cross-sectional view of the heat processing apparatus. It is a block diagram which shows a lamp | ramp and a lamp control part. It is a top view which shows an inner side from a cylindrical member. It is an expanded sectional view which shows a mode that a board | substrate is supported by the support ring group. It is a figure which shows the relationship between the film thickness difference D and (TxW).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat processing apparatus 6 Lamp control part 9 Substrate 31 Auxiliary ring 51-53 Radiation thermometer 90 Outer peripheral surface 91 Outer edge part 310 Inner peripheral surface 311 Support part 411-414, 421-424 Lamp T Support part thickness Tw Substrate thickness W Support width

Claims (8)

A heat treatment apparatus for performing a process involving heating by irradiating a substrate with light,
A group of lamps that irradiate the substrate with light;
An auxiliary ring that has an annular support portion that supports the outer edge portion of the substrate by abutting from below and extends outward from the outer edge portion;
An annular buffer ring for supporting the auxiliary ring from the outside;
With
The support width where the outer edge portion of the substrate to be supported and the support portion abut is 1.0 mm or more, and the thickness of the support portion is 0.3 mm or more,
The value expressed in square millimeters by multiplying the support width and the thickness of the support portion is 0.4 or more, and is equal to or less than the value expressed in millimeters by doubling the thickness of the substrate.
The buffer ring supports the outer edge portion of the auxiliary ring from below with an annular surface contact,
The lamp group is divided into a plurality of small groups to which power is supplied independently of each other, and the plurality of small groups include a small group that mainly emits light toward the auxiliary ring. A heat treatment device characterized. The heat treatment apparatus according to claim 1,
A heat treatment apparatus characterized in that power supplied to the small group for irradiating light mainly toward the auxiliary ring in the temperature raising step is made higher than others. The heat treatment apparatus according to claim 1 or 2,
Multiple radiation thermometers,
A lamp controller for controlling power supply to the plurality of small groups according to the measurement results of the plurality of radiation thermometers;
A heat treatment apparatus further comprising: The heat treatment apparatus according to any one of claims 1 to 3,
The heat treatment apparatus, wherein the value obtained by multiplying the support width by the thickness of the support portion is 1.5 or less. The heat treatment apparatus according to any one of claims 1 to 4,
The heat treatment apparatus, wherein the support width is 3 mm or less. A heat treatment apparatus according to any one of claims 1 to 5,
The thickness of the said support part is 0.5 millimeter or less, 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 auxiliary ring is made of silicon carbide. A heat treatment apparatus according to any one of claims 1 to 7,
The heat treatment apparatus, wherein the auxiliary ring has a cylindrical surface facing the outer peripheral surface of the substrate.

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