JPS59215718A - Infrared heat treatment apparatus for semiconductor wafer - Google Patents

Abstract

PURPOSE:To reduce a heat loss and even the temperature of the surface of a wafer by a method wherein floating gas outlets and rotating gas outlets are provided, and a wafer being gas-supported is rotated during a predetermined period of heat treatment. CONSTITUTION:A wafer 2 is disposed at a predetermined position. Thereupon, the wafer 2 is rotated in a state of floatation, while being in close proximity to the surface of a retaining plate 1, by virtue of the gas jetting out of floating gas outlets 5. The wafer 2 is furthermore forced from every direction toward the central portion by the gas emitting from positioning gas outlets 4. Then the wafer 2 halts and remains static at a position where the pushing forces are well balanced. The gas is spouted from rotating gas outlets 6 which are arranged at equal spacings on the inside concentric circle neighbouring to the circle defined by the gas outlets 5. As a result, the wafer 2 being in a state of flotation rotates in such manner that the center of the wafer 2 is retained by means of the positioning gas. In this condition, the infrared irradiation is effected, whereby there is no partial thermal loss caused by the contact with solid substances and it is possible to make uniform the temperature of the wafer surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for rapidly heating a semiconductor substrate to perform heat treatment.

2. Description of the Related Art Conventionally, a method of heating a semiconductor substrate (hereinafter referred to as a wafer), which is an object to be heated, using infrared irradiation has already been implemented. However, in general, this method places the wafer on a susceptor and heats it by irradiating infrared rays from the top surface, so the temperature of the top surface of the wafer increases rapidly, and the wafer is in contact with the susceptor, which has a large heat capacity. The delay in raising the bottom surface of the wafer causes a large temperature gradient between the top and bottom surfaces of the wafer, which may cause changes in the distribution of implanted ions in ion-implanted wafers. To avoid this, the above temperature gradient can be reduced by making the susceptor with an infrared transmitting material such as quartz and irradiating infrared rays from the bottom of the susceptor, but the infrared absorption rate of quartz and other materials is low. Since the susceptor does not easily generate heat directly, and the amount of heat escapes by heat conduction from the lower surface of the wafer to the susceptor, the temperature gradient described above cannot be improved much.

This temperature gradient is undesirable because it causes the above-mentioned change in the implanted ion distribution and also causes defects such as defects on the wafer.

In order to avoid this cause of defects, if about three protrusions are provided on the susceptor and the wafer is placed on these protrusions, the temperature gradient caused by the heat conduction can be eliminated to a considerable extent. Due to variations in radiation amount, etc.
The temperature gradient at the wafer surface cannot be eliminated.

In order to remove this temperature gradient on the narrow surface of the wafer, it is sufficient to rotate the susceptor, but the apparatus becomes complicated. The use of the trench method in continuous heat treatment equipment for mass production requires complex loading and unloading equipment for wafers, and the large heat capacity of the handling mechanisms of these equipment increases heating and cooling times. It becomes necessary,
Rapid operation is not possible, which reduces the number of wafers processed.

The present invention has been made to solve these problems, and provides a heat treatment apparatus that can perform rapid heating without creating a temperature gradient within the wafer, and that can be easily applied to flow production for mass production. It is something. This will be explained in detail below with reference to the drawings.

FIG. 1 is a vertical cross-sectional view through the center point of holding a wafer to be heat-treated in an apparatus according to an embodiment of the present invention. A holding plate 1 made of a material that easily transmits infrared rays, such as quartz, is provided with a gas outlet 3 at the center of the position where the wafer 2 is held, for maintaining the wafer 2 in a floating state. A plurality of positioning gas jet ports 4 are arranged around the discharge port 3 and distributed over a circumference 4' slightly larger than the outer circumference of the wafer 2 held thereon, and are inclined toward the discharge port 3 side. is provided. FIG. 2 is a plan view showing the arrangement of the discharge port 3 on the holding plate 1, the positioning gas jet port 4, and various gas jet ports described later. Next, a plurality of floating gas nozzles 5 are provided evenly distributed on a concentric circle 5' located between the circumference 4' where the plurality of positioning gas nozzles 4 are lined up and the discharge port 3. There is. All of these floating gas ejection ports 5 are provided perpendicularly to the holding plate 1, or all of them are provided inclined at a certain angle toward the discharge port 3 side. FIG. 1 shows the vertical case.

Further, the floating gas is distributed evenly on a concentric circle 6' located midway between the circumference 5' passing through these floating gas jet ports 5 and the discharge port 3, and is arranged at a constant angle in the tangential direction of this concentric circle and the discharge port 3. A rotational gas ejection port 6 is provided obliquely in the same direction as viewed from the position of the outlet 3. Further, the upper side of the holding plate 1 has an upper lid 7 which is made of a material such as quartz that transmits infrared rays and is made of a material that is transparent to infrared rays and is shaped to house the wafer 2 held in a floating state.
covered with Infrared ray irradiation devices 8 are provided above the upper lid 7 and below the holding plate 1, respectively, so as to irradiate the wafer 2 held in the floating state. Note that the discharge port 3, the positioning gas outlet 4, the floating gas outlet 5, and the rotating gas outlet 6 are each provided with a conduit 13 made of a material that easily transmits infrared rays, such as quartz.
14, 15 and 16 are connected so that the necessary gas can be ejected and discharged when necessary.

Next, other embodiments of the present invention will be described.

FIG. 3 is a plan view showing the arrangement of the discharge port 3 and various gas jet ports on the holding plate 1. Since the discharge port 3 and the rotating gas jet port 6 are the same as those in the previous embodiment, their explanation will be omitted. A plurality of carrier gas jet ports 9 are arranged in a row on a straight line 9' passing through the center of the discharge port 3, and are arranged at regular intervals and inclined in a fixed direction.
is provided. Furthermore, two straight lines 10' are parallel to the row of the carrier gas jet ports 9 and are in contact with both sides of the circumference 12' on the holding plate 1, which corresponds to the outer circumference of the shaver held with the discharge port 3 as the center. At regular intervals, the carrier gas outlet 9
A plurality of induced gaseous outlets 10 are provided inclined in the direction of the rows. Further, on both sides of the row of carrier gas jet ports 9, there are arranged perpendicular to the holding plate 1 or rows of carrier gas jet ports 9 at regular intervals on a straight line 11' parallel to these rows between the row of guiding gas jet ports 1o. A floating gas outlet 11 is provided so as to be inclined in the direction of . On the circumference of the holding plate 1 where the row of guiding gas jet ports 10 is in contact with, the same number of positioning gas jets are arranged between the row of carrier gas jet ports 9 and the row of floating gas jet ports 11, respectively. An outlet 12 is provided, and these positioning gas outlets I2 are inclined in the direction of a plane passing through the outlet 3 and perpendicular to the row of carrier gas outlets 9.

Of the above-mentioned jet ports, the guiding gas jet port 10 and the floating gas jet port 11 form a first group, and among the positioning gas jet ports 12, the front side 12-1 that is conveyed is the second group.
The group is also transported to the same side (rear side) J2-
2 constitutes the third group b), the carrier gas outlet 9 constitutes the fourth group, and the rotating gas outlet constitutes the fifth group 0. A conduit made of a material that easily transmits infrared rays, such as quartz, is connected to the bottom of the tube, allowing the necessary gas to be ejected and discharged when needed. Holding plate 1 like this
Besides, the upper cover 7 and the infrared ray irradiation device 8 are the same as those in the previous embodiment, so their explanation will be omitted.

Next, the operation of the apparatus of the present invention will be explained.

First, a first example will be described. In this embodiment, the holding plate 1 does not have the function of transporting the wafer, but instead holds the wafer floating in a fixed position and heats it with infrared rays. Before placing the wafer 2, a required amount of gas (for example, nitrogen gas) is ejected from each ejection port. The direction of ejection is the direction in which the through-hole spout described above is facing,
It is inclined by about 30 degrees in the direction of the arrow in FIG. 2 from the direction perpendicular to the surface of the holding plate 1. Note that the floating gas outlet 5 may be vertically oriented, inclined at an angle of about 30 degrees, or tilted, but arrows are not shown in FIG. 2. When the wafer 2 is placed in a predetermined position in such a state, the wafer 2 is held in a floating state on the holding plate 1 by the floating gas ejected from the wafer 5. Since the levitation height can be adjusted by the amount of levitation gas ejected, levitation of 0.5 or less is sufficient. Furthermore, the wafer 2 is pushed toward the center of the wafer 2 from each positioning gas outlet 4 by the positioning gas ejected from the wafer 4 . Therefore, since the ejection ports are distributed, Ueno 2 is pushed toward the center from each direction and comes to rest at a place where these forces are balanced. It is sufficient that the jet ports are arranged so that this stationary point is concentric with a circle centered on the discharge port 3, so in the case of the first embodiment, it is sufficient that they are evenly distributed.

Next, the rotation of the wafer 2 will be explained. When rotating gas is ejected in a direction inclined at approximately 30 degrees with respect to the mW direction from the rotating gas nozzles 6 evenly distributed on a concentric circle inside the levitating gas nozzle row, Ueno-2 in a levitating state is positioned. It rotates while being held centered by gas.

If the top lid 7 is closed in this state and the infrared irradiation device 8 is turned on, the wafer 2 will be irradiated with infrared rays from above and below.
heats up rapidly. In the embodiment, when the energy irradiation density of infrared rays is set to about 20 to 30 W/ca, the wafer 2 can be heated from room temperature to a high temperature of 1000° C. or more in about 10 seconds. Moreover, the temperature difference between the upper and lower surfaces of the wafer 2 can be controlled by adjusting the power supplied to the upper and lower infrared irradiation devices 8.
Balance can be easily maintained. In addition, Ueno
Since the wafer 2 is rotated, temperature differences on the same surface of the wafer 2 due to variations in the arrangement of the infrared irradiation device 8 and the amount of infrared irradiation can be eliminated, and uniform heating can be achieved.

Note that the lower surface of the wafer 2 may be cooled by gas jetting by increasing the amount of irradiation from the lower infrared irradiation device 8 by an amount corresponding to the amount of cooling.

Next, the operation of the second embodiment will be explained.

FIG. 6 is a layout diagram of the discharge port 3 and each jet port on the holding plate 1 of this embodiment, and the arrow indicates the direction in which the direction of the jet port is inclined from the perpendicular line on the holding plate 1. Also in this embodiment, the inclination angle is approximately 30 degrees from the perpendicular.

Of these jet ports, gas is spouted from the beginning from the first group of induction gas and floating gas jet ports 10 and 11, and gas of this group is constantly spouted during operation. Next, add 1 positioning gas to the third group.
2-2, the fourth group of carrier gases are ejected from 9, and then the Ueno 2 is placed at the right end in FIG. 6 between the two rows of induced gas ejection ports 10. floats up from the holding plate 1 by about 0.5 mm by the floating gas, is guided by the guiding gas onto the center line of the conveying path, and is conveyed by the carrier gas until it reaches just above the discharge port 3 in the central part of FIG. When it reaches this position, its progress is stopped by the ejected flow of the third group of positioning gases already ejected from 12-2. At this time, the ejection of the fourth group of carrier gases is stopped, and at the same time, the second group of positioning gases and the fifth group of rotational gases are ejected from the respective ejection ports 12-1 and 6. In this state, Ueno Tsuta 2 remains floating from the holding plate 1 with the levitation gas of the first group, and is also centered directly above the discharge port 3 by the guiding gas of the first group and the positioning gas of the second and third groups. It is positioned at this position and starts rotating by the rotation gas of the fifth group.

At this time, the infrared irradiation device 8 is already turned on, so the wafer 2, which is floating and rotating at a certain position,
Both sides of the bottom (bottom side) are heated to a minimum.

Next, in order to carry out the wafer 2 after heat treatment for a predetermined time, if the ejection of the positioning gas of the third group is stopped and the ejection of the carrier gas of the fourth group is restarted,
The positioning gas of the second group ejected from 2-1 and the carrier gas of the fourth grouto cause the machine to start moving to the left in FIG. 3, and thereafter move to the left end using only the carrier gas.

Note that the rotational gas of the fifth group may be ejected only when the wafer 2 is rotated, or may be ejected all the time like the induction gas and floating gas of the first group.

In the case of this second embodiment, the description is given in Japanese Patent Application No. 103524/1983 filed by the present applicant entitled "Method and Apparatus for Continuous Heat Treatment of Semiconductor Substrates" at the right and left ends of the running section of the wafer 2 shown in FIG. By providing a wafer supply cassette and a wafer storage cassette, it is possible to easily automate the operation from cassette to cassette.

As described above, in the apparatus of the present invention, the wafer 2 is floated by the ejected gas, so there is no partial heat loss due to contact with solid objects, and furthermore, since it is rotating during the predetermined heat treatment period, it Temperature unevenness on the surface of the wafer 2 due to variations in the arrangement of the irradiation device 8 and the amount of irradiation can also be equalized.

Furthermore, since floating transportation is possible, automation of continuous heat treatment equipment can be easily performed. Furthermore, since there is no need to heat parts with large heat capacity, rapid heating and rapid cooling can be easily carried out, and the practical effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an apparatus according to an embodiment of the present invention through the center point holding the wafer. FIG. 2 is a layout diagram of gas discharge ports and jet ports on the holding plate of the device shown in FIG. 1. FIG. 6 is a diagram illustrating the arrangement of gas discharge ports and jet ports on a holding plate of an apparatus according to another embodiment of the present invention. In the figure, 1 is a holding plate, 2 is a wafer, 3 is a discharge port,
4 is a positioning gas outlet, 5 is a floating gas outlet, 6 is a rotating gas outlet, 7 is an upper lid, 9 is a carrier gas outlet, 1
0 is a guiding gas outlet, 11 is a floating gas outlet, 12-1
．． 12-2 is a positioning gas outlet. Patent applicant: Kokusai Denki Co., Ltd. Agent: Toshihito Yamamoto, patent attorney

Claims (1)

[Scope of Claims] (1) A heat treatment apparatus that heats a semiconductor substrate with infrared rays, which includes: a holding plate that is provided with a jet port that blows out gas so as to hold the semiconductor substrate horizontally in a floating state and that transmits the infrared rays; an upper cover that covers the upper side of the holding plate and transmits the infrared rays so as to house the semiconductor substrate held in a floating state on the holding plate; and a top cover that is levitated from below the holding plate and above the upper cover. The holding plate includes an infrared irradiation device that irradiates infrared rays to each of the semiconductor substrates held in the floating state, and the holding plate has an outlet for gas that maintains the floating state at the center of the position where the semiconductor substrate is held in the floating state. and are distributed over a circumference slightly larger than the outer diameter of the semiconductor substrate with this discharge port as the center, and are provided in a direction inclined toward the discharge port by a certain angle from a perpendicular to the holding plate. a plurality of positioning gas outlets, and a plurality of floating gases that are evenly distributed on non-concentric circles and provided in a fixed direction at intermediate positions between the circumference passing through the positioning gas outlets and the gas discharge port; A spout and
They are evenly distributed on a concentric circle located midway between the circumference passing through the floating gas outlet and the gas outlet, and are arranged at a constant angle in the tangential direction of this concentric circle and viewed from the position of the gas outlet. What is claimed is: 1. An infrared heat treatment apparatus for semiconductor substrates, characterized in that the device includes a rotating gas outlet inclined in the same direction. 2. The infrared heat treatment apparatus for semiconductor substrates according to claim 1, wherein the plurality of floating gas jet ports are provided in a direction perpendicular to the holding plate. 3. The infrared heat treatment apparatus for a semiconductor substrate according to claim 1, wherein the plurality of floating gas ejection ports are provided to be inclined at a predetermined angle toward the discharge port side with respect to the holding plate. infrared heat treatment equipment. 4. In a heat treatment apparatus that heats a semiconductor substrate with infrared rays, a holding plate that is provided with a jet port that blows out gas so as to horizontally transport and hold the semiconductor substrate in a floating state and that transmits the infrared rays; a top cover that covers the upper side of the holding plate and transmits infrared rays so as to store the semiconductor substrate transported and held in a floating state; The holding plate includes an infrared irradiation device that irradiates infrared rays to each of the semiconductor substrates held in the floating state, and the holding plate has an outlet for the gas that maintains the floating state at the center point of the position where the semiconductor substrate is held in the floating state, and an outlet for the gas that maintains the floating state. A line of carrier gas outlets arranged at regular intervals on a straight line passing through the center of the discharge port and tilted in a certain direction on a plane perpendicular to the holding plate; They are arranged in rows on two straight lines that are parallel to each other and that are in contact with a circumference on the holding plate corresponding to the outer circumference of the semiconductor substrate held at the position where the semiconductor substrate is held, one on each side of this circumference. guiding gas jetting ports provided at regular intervals and inclined at a certain angle toward the row of carrier gas jetting ports; and a row of guiding gas jetting ports provided midway between the row of guiding gas jetting ports and the row of carrier gas jetting ports. floating gas jetting ports that are arranged in parallel rows and spout gas in a fixed direction; and the holding plate, which is slightly larger than the outer circumference of the semiconductor substrate, for positioning the semiconductor substrate at a position where the semiconductor substrate is to be held. positioning gas outlets distributed on the upper circumference and inclined in the direction of a plane passing through the center of the force gas outlet and perpendicular to the row of the carrier gas outlets; and the gas outlet; and a circumference passing through the positioning gas outlet, and are arranged at a constant angle in the tangential direction of the concentric circle and inclined in the same direction when viewed from the position of the discharge outlet. 1. An infrared heat treatment apparatus for semiconductor substrates, characterized by comprising a gas outlet. 5. The infrared heat treatment apparatus for semiconductor substrates according to claim 4, wherein the plurality of floating gas jet ports are provided in a direction perpendicular to the holding plate. 6. In the infrared heat treatment apparatus for semiconductor substrates as set forth in claim 4, the plurality of floating gas outlets are inclined at a predetermined angle with respect to the holding plate in the direction of the row of the carrier gas outlets. The infrared heat treatment apparatus for the semiconductor substrate.