JPH07126094A - Silicon single crystal producing device - Google Patents

Abstract

PURPOSE:To provide the device capable of securing the pressure strength of gate oxidized film while maintaining a high-speed pull rate in producing single crystal silicon. CONSTITUTION:The silicon single crystal production device based on Czochralski process is so designed that a seed crystal 14 is dipped in the silicon melt 4 in a quartz crucible 5 and then pulled to grow a silicon single crystal 1. A hydrogen gas 10 is used as carrier gas. With this device, since the silicon single crystal 1 is produced in a hydrogen gas atmosphere; therefore, at the same time, an annealing operation can be made to secure the pressure strength of a gate oxidized film. Therefore, the pressure strength of the gate oxidized film of a device formed can be secured without requiring addition of new process(es) after pull; Also, the pull rate for the single crystal is not decreased, thus not impairing silicon single crystal production efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon single crystal manufacturing apparatus by the CZ method (Czochralski method) in which a silicon polycrystal is melted, a seed crystal is immersed, and this is pulled to grow a silicon single crystal.

[0002]

2. Description of the Related Art There are some silicon single crystal manufacturing apparatuses using the FZ method (floating zone method) and the CZ method (Czochralski method). When manufacturing a silicon wafer having a low resistance, an apparatus using the CZ method is used. Here, the CZ method is a method in which a silicon polycrystal is melted in a quartz crucible to immerse a seed crystal, and the crucible for taking the seed crystal is pulled up while rotating to grow a silicon single crystal.

The pulling of single crystal silicon is carried out in a reduced pressure argon atmosphere (1000 to 2000 Pa) using argon as a carrier gas in order to remove SiO evaporated from the surface of the silicon melt. Also,
In order to improve production efficiency, the pulling speed is relatively high, averaging 1.0 mm / min.

Although the single crystal silicon manufactured under such a condition is used today, the gate oxide film is becoming thinner along with the high integration of devices. As a result, the electric field applied to the gate oxide film is relatively increased. Therefore, the improvement of the oxide film withstand voltage has become an important issue. The cause of the deterioration of the withstand voltage characteristic of the oxide film is mainly due to the wafer processing process such as foreign substances, microscopic smoothness of the surface, and contamination by alkali ions and heavy metals, and the crystal structure of the silicon single crystal, that is, It is divided into those attributed to bulk properties.

Among them, the bulk characteristics are closely related to the pulling rate at the time of pulling single crystal silicon, and it is known that the slower the pulling rate is, the higher the withstand voltage strength of the gate oxide film is. Specifically, in relation to the bulk stacking fault, when the crystal is pulled at a pulling rate of about 0.4 mm / min or less, the crystal is significantly improved, and the oxide film withstand voltage is improved.

However, as described above, in the current mass production process, the lowering of the pulling speed is directly related to the deterioration of the production efficiency, and therefore the pulling speed is about 1.0 mm / mi.
n is the solution strength of the silicon ingot or sliced semiconductor wafer after pulling at a high temperature of about 1300 ° C or higher, or post-treatment such as wafer heat treatment in a hydrogen gas atmosphere to improve the withstand voltage strength of the gate oxide film. Improvements are being made.

[0007]

However, each of the measures for improving the withstand voltage strength of the gate oxide film of such a device means adding a new step to a series of wafer manufacturing processes, which increases the manufacturing cost. It will be.

Therefore, an object of the present invention is to manufacture a silicon single crystal which can maintain the withstand voltage strength of a gate oxide film without performing a post-treatment after the pulling while maintaining a high pulling rate at the time of producing the single crystal silicon. To provide the technology.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0010]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, the silicon single crystal manufacturing apparatus of the present invention is a silicon single crystal manufacturing apparatus by the CZ method, that is, a seed crystal is immersed in a silicon melt in a quartz crucible and the seed crystal and the quartz crucible are rotated. An apparatus for producing a silicon single crystal by pulling a crystal to grow a silicon single crystal, in which hydrogen gas is used as a carrier gas used in the growth stage of the silicon single crystal.

[0012]

According to the above-described silicon single crystal manufacturing apparatus, since the silicon single crystal is manufactured in the hydrogen gas atmosphere, in order to secure the withstand voltage strength of the gate oxide film at the same time in the growth stage of the silicon single crystal. Will be annealed. Therefore, it becomes possible to secure the withstand voltage strength of the gate oxide film of the formed device without adding a new process after the pulling.

Further, since the above-mentioned annealing treatment can be performed without lowering the pulling rate during the production of single crystal silicon, the production efficiency is not deteriorated.

[0014]

Embodiments of the present invention will now be described in more detail with reference to the drawings.

FIG. 1 is a sectional view showing a silicon single crystal manufacturing apparatus according to an embodiment of the present invention.

The present silicon single crystal production apparatus is for producing a silicon single crystal 1 by the CZ method. The central portion of the pulling furnace 2 located below is surrounded by a graphite crucible 3 that supports deformation at high temperature. A quartz crucible 5 in which a polycrystalline silicon melt 4 is housed is located inside. On the bottom surface of the graphite crucible 3, there is a rod 6 having not only a rotating mechanism but also a raising mechanism.
Are connected to maintain the liquid surface of the silicon melt 4 at a constant position during the growth stage of the silicon single crystal 1 so that the temperature distribution near the liquid surface is not changed.

On the outer periphery of the graphite crucible 3, a silicon melt 4
A graphite heater 7 for heating and maintaining a constant temperature, and a shield plate 8 for preventing heat of the graphite heater 7 from radiating to the outside are arranged.

A gas supply port 11 for supplying hydrogen gas 10 as a carrier gas for effectively discharging SiO vaporized from the surface of the silicon melt 4 through the exhaust port 9 is provided in the upper portion of the pulling furnace 2. Further, an optical sensor 12 for optically detecting the positional movement of light from the meniscus portion formed by the silicon single crystal 1 lifting the liquid surface as an increase / decrease in diameter, and controlling the diameter of the growing silicon single crystal 1 to be constant is provided. Has been.

Above the pulling furnace 2, there is provided a crystal take-out section 13 which opens into the pulling furnace 2 and above which is provided a wire winding device 15 for pulling up the seed crystal 14 while rotating it.

An opening / closing door 16 for taking out the pulled silicon single crystal 1 from the side is provided in the crystal take-out portion 13, and, like the pulling furnace 2, SiO from the silicon single crystal 1 is effectively used. A gas supply port 18 for supplying the hydrogen gas 10 to be exhausted from the exhaust port 17 is opened. Therefore, in this embodiment, the silicon single crystal 1 is manufactured in a hydrogen gas atmosphere.

The wire winding device 15 immerses the seed crystal 14 held by the seed crystal holder 20 provided perpendicularly to the silicon melt 4 by the wire 19 into the polycrystalline silicon melt 4, While rotating, for example about 1.
The silicon single crystal 1 is pulled up at a rate of 0 mm / min, whereby the silicon single crystal 1 is grown subsequent to the seed crystal 14.

As described above, in the silicon single crystal manufacturing apparatus of this embodiment, as described above, the hydrogen gas 10 is used as the carrier gas for discharging SiO, and the silicon single crystal 1 is manufactured in the hydrogen gas atmosphere. Since it is carried out in the inside, an annealing treatment for securing the withstand voltage strength of the gate oxide film is simultaneously performed in the growth stage of the silicon single crystal 1.

Therefore, after the pulling, the gate of the formed device is added without adding a new process such as solution treatment of a silicon ingot or a sliced semiconductor wafer or heat treatment in a hydrogen gas atmosphere. It is possible to secure the pressure resistance of the oxide film.

This will be described in more detail. The yield rate of non-defective oxide film of devices formed on a semiconductor chip made of the silicon single crystal 1 manufactured by the silicon single crystal manufacturing apparatus of this embodiment, that is, the breakdown voltage on a semiconductor chip base. According to an experiment conducted by the present inventors, the rate of obtaining semiconductor wafers having a breaking strength of 8 MV / cm or more and an occurrence rate of 80% or more is 5
It was 0 to 70%. On the other hand, a silicon single crystal manufactured by a conventional silicon single crystal manufacturing apparatus (in a state before being subjected to a post-treatment such as solution treatment) has an oxide film breakdown voltage non-defective product acquisition rate of 10 to 20%.

Therefore, it is confirmed that there is a remarkable effect in securing the withstand voltage strength of the gate oxide film in the formed device.

Further, according to the silicon single crystal manufacturing apparatus of this embodiment, the annealing treatment is performed while pulling at a high speed of, for example, about 1.0 mm / min without lowering the pulling speed at the time of manufacturing the single crystal silicon 1. Since it is possible, it does not deteriorate the production efficiency.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the silicon single crystal manufacturing apparatus of this embodiment, in order to perform the annealing treatment efficiently,
The gas supply ports 11 and 18 for supplying the hydrogen gas 10 are provided at a total of two places, that is, the upper part of the pulling furnace 2 and the crystal extracting part 13, but it is also possible to provide them at only one or at three or more places. is there. Therefore, the silicon single crystal 1
The hydrogen gas 10 can be supplied in various ways, as long as the production of is performed in a hydrogen gas atmosphere.

[0029]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) That is, according to the silicon single crystal manufacturing apparatus of the present invention, since the silicon single crystal is manufactured in a hydrogen gas atmosphere, at the growth stage of the silicon single crystal, the gate is parallel to this. Annealing treatment is performed to secure the pressure resistance of the oxide film.

(2) Therefore, since it becomes possible to secure the withstand voltage strength of the gate oxide film of the formed device without adding a new process after the pulling, without increasing the manufacturing cost. Therefore, the manufacturing apparatus can be more suitable for the mass production process.

(3) Further, since the above annealing treatment can be performed while maintaining the pulling rate at the time of manufacturing single crystal silicon at a high speed, the production efficiency is not deteriorated due to the lowering of the pulling rate.

[Brief description of drawings]

FIG. 1 is a sectional view showing a silicon single crystal manufacturing apparatus according to a first embodiment of the present invention.

[Explanation of symbols]

 1 Silicon Single Crystal 2 Pulling Furnace 3 Graphite Crucible 4 Silicon Melt 5 Quartz Crucible 6 Rod 7 Graphite Heater 8 Shielding Plate 9 Exhaust Port 10 Hydrogen Gas 11 Gas Supply Port 12 Optical Sensor 13 Crystal Extraction Section 14 Seed Crystal 15 Wire Winding Device 16 Open / close door 17 Exhaust port 18 Gas supply port 19 Wire 20 Seed crystal holder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masato Fujita 5-20-1 Kamimizuhoncho, Kodaira-shi, Tokyo Incorporated Hitachi, Ltd. Semiconductor Division (72) Inventor Keiichi Anji 3-chome, Fujihashi, Ome-shi, Tokyo Address 2 Inside Hitachi Tokyo Electronics Co., Ltd.

Claims (2)

[Claims] 1. A silicon single crystal according to the Czochralski method in which a seed crystal is immersed in a silicon melt in a quartz crucible, and the seed crystal is pulled up while rotating the seed crystal and the quartz crucible to grow a silicon single crystal. A silicon single crystal manufacturing apparatus, wherein hydrogen gas is used as a carrier gas used in the step of growing the silicon single crystal. 2. The gas supply port for supplying the hydrogen gas,
The silicon single crystal manufacturing apparatus according to claim 1, wherein the apparatus is provided in the pulling furnace and the crystal extracting section.