JPS62252932A - Heat-treating apparatus for semiconductor wafer - Google Patents

Abstract

PURPOSE:To simply heat treatment in space-saving in a heattreating apparatus for a semiconductor wafer by using a rectangular heat-treating furnace body surrounded by a heater therearound, and attaching a quartz arm which can insert a wafer by floating without contact with the furnace body. CONSTITUTION:A wafer 1 is placed on a guartz arm 2 made of two quartz, the arm 2 is inserted into a box-shaped quartz rectangular treating furnace 3 to be heat-treated for a necessary time. The furnace 3 has at least a width slightly larger than the diameter of the wafer 1, a height of the total of the thickness of the wafer and the thickness of the arm in thickness of a space in which the wafer can be inserted by floating. The furnace 3 is covered with cartridge type heater block 4 made of a material, such as kanthal wire.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a single-wafer electric furnace for oxidizing silicon wafers, introducing and diffusing impurities, or heat-treating silicon wafers in the production of semiconductor devices.

2. Related Art Conventionally, as shown in FIG. 5, silicon wafers 1 are loaded on a quartz boat 21 to a thickness of about 1 cm, and the silicon wafers 1 are inserted into a quartz furnace core tube 22. The quartz furnace core tube 22 is usually made of a wound wire made of a material such as Kanthal wire, fixed with an insulating holder, and surrounded by a heating element 23 completely wrapped with heat insulating material, which draws a large amount of current. By pouring the quartz furnace core tube 2
2'i It can be maintained at a high temperature of about 900 to 12oO°C.

The quartz furnace core tube 22 has a gas inlet port 2 which is usually narrowly constricted at one end.
4, through which gas necessary for processing silicon wafers can flow. Although not shown in the drawings, a part of the controller that controls the temperature of the furnace body and a space cabinet that controls all gases are always included in the system.

For example, when oxidizing silicon, it is sufficient to insert the aforementioned quartz boat 21 into the center of the furnace body using a boat loading device or the like, and then flow dry oxygen through the gas inlet for a period of time to obtain the required oxide film thickness. Also, a method is often used in which oxidation is carried out by performing mixed combustion of hydrogen and oxygen and flowing water vapor, which is an oxidizing species. Furthermore, with the recent miniaturization.

The problem is that minute dust generated when the furnace core tube 22 and quartz boat 21 rub against each other scatters onto the silicon wafer 1, reducing the overall yield of integrated circuits on the silicon wafer 1. It is often seen that a so-called quartz fork 26 is used. This is done by placing the quartz boat 21 on the tip of the quartz fork 26 mentioned above, floating the quartz fork together, and placing the quartz boat 21 in the center of the quartz furnace core tube 22 without completely touching the quartz boat 21 with the quartz furnace core tube 22. This is a so-called soft landing device that can be placed in the center of the furnace body, and is an effective measure against dust.

However, as the diameter of the silicon wafer 1 becomes larger, the soft landing device described above becomes extremely cumbersome, and vertical furnaces have also begun to be considered in order to save energy and space. Simply put.

As shown in FIG. 6a, the conventional horizontal furnace is simply made vertical. Unlike quartz boats for horizontal furnaces.

A quartz boat 26 is used which is slightly inclined to prevent the silicon wafer 1 from falling and which holds the wafer therein.

In this case, unlike a large soft landing device for a horizontal furnace, by supporting the first quartz boat 26 from below, it is possible to prevent the first quartz furnace core tube 22 and the quartz boat 26 from coming into contact with each other. Therefore, as a method for inserting wafers, a vertical furnace is easier to manufacture than a horizontal furnace because it takes up less space.

Problems to be Solved by the Invention As mentioned above, in addition to increasing the size of horizontal furnaces, studies are also being conducted on vertical furnaces for large diameter wafers. However, the basic concept is that a large number of wafers are loaded onto a quartz boat and heat treated.

In other words, the quartz furnace core tube has a cylindrical shape that is thicker than the diameter of the wafer. Therefore, the diameter is %8 inches or 20 (7
) for a wafer with an inner diameter of 10 inches or approximately 25
A quartz hearth tube or a silicon carbide hearth tube is required. In addition, heat-treating all large diameter wafers requires taking in and out all items with large heat capacity, and there are many technical problems such as heat uniformity and heat retention. Furthermore, as the diameter of the wafer becomes larger, not only a quartz furnace core tube but also a variety of materials such as a quartz boat or a quartz fork for soft landing are required to be made larger. From installation to cleaning to maintenance, the inconvenience of handling only increases. Of course, considering other semiconductor devices and the like, it seems appropriate to manufacture in a lot structure of 25 or 50 pieces at present, where the cassette-to-cassette method is mostly adopted. However, with the progress of larger diameter wafers, instead of the conventional lot structure consisting of many wafers, each wafer is
This increases the need for wafer management in which wafers are moved one by one, rather than being transported between devices in a carrier loaded with several wafers.

As a means to solve the problem, a rectangular parallelepiped heat treatment furnace surrounded by a heating element using a cartridge heater was used, and inside the furnace,
A simple and space-saving method of heat treatment is adopted by attaching a quartz arm that allows a single semiconductor wafer to be floated and inserted without contacting the furnace body. Also, attach the cap to the quartz arm mentioned above.

Place a lid on the furnace body, or take measures to allow gas to flow through the quartz arm.

action Therefore, the present invention is directed toward increasing the diameter of wafers.

By introducing a single wafer processing method to the electric furnace, we will be able to demonstrate the future direction of process control for each wafer and
Good heat uniformity is an advantage of the Kyoha style.

It can fully demonstrate the ease of sterilization, ease of maintenance, space saving, etc.

Embodiments As mentioned above, the basic type of the present invention only needs to be able to heat treat one large-diameter wafer. Therefore, as shown in the perspective view shown in FIG. It is characterized by heat treatment for the required time. The processing furnace 3 only needs to have a width that is at least slightly thicker than the diameter of the wafer 1, and a thickness in the height direction that is equal to the thickness of the wafer plus the thickness of the quartz arm, and has enough space to allow floating insertion. For example, when considering an 8-inch wafer, the width is 26C1n when viewed from the front.

The size should be about 3 to 6 in height, and the soaking length is 40
(7) or above is sufficient. That is, the long side of the opening of the processing furnace 3 constituting the furnace core is 2C smaller than the diameter of the wafer 1.
11 or more, and the short side of the opening is preferably 11 or more larger than the sum of the thickness of the wafer and the thickness of the arm 2. Naturally, the rectangular processing furnace 3 is surrounded by a cartridge type heater block 4 made of a material such as Kanthal wire.

The wafer transport mechanism is simple and has few failures, and is inserted into and taken out of the processing furnace 3 by preparing two quartz rods and placing the wafer S1 on them. In this case, when the wafer is placed directly on the quartz arm 2 on which the wafer is placed, the contact area with the wafer becomes large and if heat recovery characteristics become a problem, the small protrusion 5 shown in Figure 2 & is removed from the quartz arm. It may be provided in a part of 2. A wafer is placed on this protrusion S and is supported at a minimum of three points, and in this case, there is almost no problem with the thermal uniformity characteristics at those points. Furthermore, it is recommended to provide a reinforcing frame 6 to the two quartz arms 2 and attach a cap 7 to the quartz arm 2 so that the opening of the processing furnace can be covered when the wafer 1 enters the processing furnace 3. This seems like a better direction. In order to insert these quartz arms 2 in a floating state without contacting the processing furnace 3, the quartz arms 2. A lift mechanism part 8 is installed which can lift the entire cap 7, push it into the furnace core tube, and pull it down. In addition, the insertion speed and the like may be determined by newly connecting the lift mechanism to a power source.

One end of the processing furnace 3 is open for the entry and exit of wafers, and the other end is provided with a gas inlet 9, as shown in FIG. 2, so that atmospheric gas can be introduced. Furthermore, it is also possible to use the aforementioned quartz arm 2 as a method of introducing another gas. In other words, by using one end of the two quartz rods as an inlet for introducing gas from the outside, one
It is also possible to introduce oxygen gas into the processing furnace 3 from two people using one arm, and then introduce and mix hydrogen gas from the other arm 2B to obtain water vapor, which is an oxidizing species.

Further, FIGS. 3 and 4 show the carrier groove in front of the electric furnace before and after insertion when, for example, wafers 1 are processed one by one. The wafer 1 is conveyed by a belt 6 or by air and placed on a wafer support 1 cm in front of the processing furnace 3 (FIG. 3a).

After that, the quartz arm 2 is extended and inserted under the wafer 1, and the quartz arm 2 is slightly lifted by the interlocked lift mechanism 8 (FIG. 3b), and the wafer 1 is placed on the aforementioned protrusion S. It is inserted into the processing furnace 3 by the forward motion of the lift mechanism.

Furthermore, in order to transfer the wafer to the wafer support 1 cm described above, for example, as shown in FIG. Move the entire wafer in an arc while keeping it horizontal. Let it stand still at the highest point (position B in FIG. 4) as shown in FIG. The carrier 11 is lowered from the position B indicated by the dotted line in FIG. 4 to the position indicated by the solid line 11'. By doing so, the wafer on the carrier 11 is transferred to the processing furnace wafer support 1 cm located below it, and then inserted into the processing furnace 3 by the aforementioned quartz arm 2. Conversely, when taking out the wafer 1, use 1 quartz arm 2.

The wafer 1 pulled out from the processing furnace 3 is transferred by lowering the quartz arm to the support 1 cm and retreating. Next, the carrier 11 that had been lowered is pushed up by the support rod 12 and moved from the support 1o. Because it can be raised high, wafer 1
is transferred to a conveying body, and is moved in a circular arc to the position shown in FIG.

In order to realize progress management of each wafer, the present invention
Heat treatment, which used to be a batch processing method, is now a single-wafer processing method, and the advantage of this is that the equipment that requires large size and high power consumption can be made very small as wafers become larger in diameter. It is a space-saving and energy-saving design that uses less electricity because the internal volume is smaller. Furthermore, when a large number of wafers are processed, it takes a long time to recover the original electric furnace temperature.

The equipment used to require a long soaking length, but since it processes a single sheet, it can now be heated without worrying about its recovery characteristics.
Both the reproducibility and the reproducibility are very good.

Further, the soaking length only needs to be at most twice the wafer length, and a large space is not required. Also, the soft landing device
In the conventional method for processing a large number of wafers, the equipment becomes large and the temperature recovery characteristics of the quartz furnace tube and wafers are also extremely poor. However, in the second embodiment of the present invention, the design is simple and does not take up much space, which is very advantageous for future enlargement of the diameter. The problem is how to deal with the drawback of mass production compared to the conventional method, but since most other processes are also increasing in single-wafer processing, it is said that if one sheet is processed, it can be immediately transferred to the next process. If you use this method, it seems that there will be no problems.

This is because, as miniaturization progresses, the process temperature and short time in high-temperature electric furnace heat treatment are also progressing. However, if we consider, for example, X-ray steppers and electron beam exposure,
Although it requires much longer time than conventional original batch exposure and takes more time due to microfabrication, electric furnace processing allows for thinning of the oxide film and, for example, it takes less time to form a gate oxide film of 1 cm. With the 900°C pyrogenic method, this can be done in just 5 minutes. Further, in many cases, 5 minutes is actually sufficient for annealing after ion implantation, and at present, it is simply a conventional practice to extend the annealing to 30 minutes. Therefore, even with a single-wafer type electric furnace, there is no problem in mass production. Since it is possible to save space and energy, there will be no problem in mass production if several stages of heat treatment furnaces according to the present invention are arranged to take full advantage of the homogeneity within the wafer of the single wafer processing method. The good homogeneity within the wafer that I just mentioned is also a feature of the present invention, which uses a single-wafer processing method, compared to the batch method.

The heat temperature distribution received by the wafer is good because the various heat capacities are small, and further, the uniformity is also improved because temperature control is easy.

Effects of the Invention According to the present invention, only one semiconductor wafer can be inserted floatingly without contacting the two furnace bodies, making it possible to perform heat treatment in a simple and space-saving manner. Furthermore, the soaking length of the furnace can be shortened, and highly homogeneous heat treatment within the wafer can be performed with good mass productivity.

[Brief explanation of drawings]

Figures 1a, b, and c are schematic perspective views, side views, and front views of essential parts of a heat treatment furnace according to an embodiment of the present invention, and Figure 2a is a schematic diagram of main parts. C is a perspective view of an example of a quartz arm for actually loading and inserting wafers, and FIG. 2 is a perspective view of the furnace body. Figures 3a and 3b are diagrams showing the operating state of the wafer transport section in front of the furnace in an apparatus according to an embodiment of the present invention, and Figure 4a
, b are operational state diagrams of the wafer transfer section of the same apparatus, and Fig. 5 a,
b is a conventional horizontal heat treatment furnace -1... silicon wafer, 2... quartz arm, 3... rectangular processing furnace, 4... heater block . Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure (0L) 2 quartz arm Cb) Figure 2 (0-n (bn CC) Figure 3 (0-) Figure 4 (α) tt tZ (b) Figure 5 ?1 ?3 Figure 6 Turtle (btsuku2 〆＼〜

Claims (5)

[Claims] (1) A rectangular heat treatment furnace core with an opening at one end, a heating element surrounding the furnace core with a heater, and a semiconductor substrate that can be loaded without touching the furnace core. 1. A heat treatment apparatus for semiconductor wafers, comprising an arm body into which the semiconductor substrate can be inserted. (2) The long side of the opening of the furnace core is at least 2 cm larger than the diameter of the semiconductor substrate, and the short side of the opening is 1 cm larger than the sum of the thickness of the semiconductor substrate and the thickness of the arm body.
2. The heat processing apparatus for semiconductor wafers according to claim 1, which has a size larger than that and further includes a pipe connected to the other end opposite to the opening through which a processing gas can be introduced. (3) The arm body consists of at least two or more thin tubes,
Claims characterized in that each end of the thin tube has an opening, and a cap is attached to the arm body to cover the opening of the furnace core when the arm is inserted into the furnace core. The semiconductor wafer heat treatment apparatus according to item 1. (4) The semiconductor wafer heat treatment apparatus according to claim 1, further comprising a control section for controlling power of the heating element. (5) The semiconductor wafer heat treatment apparatus according to claim 2 or 3, further comprising a source cabinet section that can control the introduction of necessary gas into each thin tube.