JPH07109195A - Crystal growth apparatus and crystal growth method - Google Patents

Abstract

(57) [Summary] [Structure] Above the crucible 13, at least three heating means 21, 22, 24 and /
Alternatively, a crystal growth apparatus is provided with a cooling means 23. [Effect] When pulling up the Si single crystal 17, the additional patterns of the powers P1, P2, P3, and P4 required for heating and cooling are set in advance, respectively, so that Si can be cooled at predetermined cooling rates in four temperature ranges. Single crystal 17
Can be cooled. Therefore, the quality of the Si single crystal 17 can be improved, and the O
It is possible to reduce the SF density, increase the amount of precipitated oxygen inside the wafer after the heat treatment, and improve the oxide film withstand voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal growth apparatus and a crystal growth method, and more particularly, it is used for growing a single crystal used as a semiconductor material, for example, and pulls the single crystal while controlling a cooling rate. The present invention relates to a crystal growth apparatus and a crystal growth method.

[0002]

2. Description of the Related Art There are various methods for pulling a crystal, one of which is the Czochralski method (hereinafter referred to as the CZ method). FIG. 3 is a sectional view schematically showing a crystal growth apparatus used in the conventional CZ method, and 11 in the figure shows a chamber. The chamber 11 is formed by a container 12, is kept at a low pressure by a vacuum pump (not shown), and Ar gas is introduced from the upper chamber 11a. A crucible 13 having a cylindrical shape with a bottom is provided at a substantially central portion of the chamber 11, and a heater 14 is provided on the outer periphery of the crucible 13 concentrically with the crucible 13. The heater 14 melts the crucible 13 inside the crucible 13. A melt 15 of a silicon (hereinafter referred to as Si) crystal raw material is filled. A pulling shaft 16 is arranged on the central axis of the crucible 13. The seed crystal 16 a attached to the tip of the pulling shaft 16 is brought into contact with the surface of the melt 15 to pull up the pulling shaft 1.
By pulling 6 up, the Si single crystal 17 formed by solidifying the melt 15 is grown and cooled.

A stacking fault is one of the items for evaluating the quality of the pulled Si single crystal 17 (evaluation item (1)). The stacking fault is caused by the Si deposited in the Si single crystal 17.
It is said that the compound oxygen in the oxide returns to oxygen and is caused by this. To suppress the occurrence of this stacking fault,
A method of rapidly cooling (hereinafter referred to as quenching) when pulling up the Si single crystal 17 has been proposed (JP-A-1-31).
3384).

FIG. 4 shows a Si single crystal 17 during pulling.
It is sectional drawing which showed typically the conventional crystal growth apparatus comprised so that it may be rapidly cooled. In the figure, 13 has shown the crucible. A cooling cylinder 31 formed in a substantially cylindrical shape is disposed and fixed at a predetermined position above the crucible 13, a circulation chamber 31a is formed in the cooling cylinder 31, and a cooling liquid is introduced into the circulation chamber 31a. A pipe and a discharge pipe (both not shown) are connected. Then, a cooling liquid such as water is circulated in the flow chamber 31a to pull up the silicon single crystal 17
Is to be cooled. When a crystal is grown using the apparatus configured as described above, 1050 ° C. to 8 ° C.
Cooling time to reach 50 ° C is 140 minutes or less (cooling rate 1.4
℃ / min or more), the Si single crystal 17
Is being raised while being rapidly cooled.

Another item for evaluating the quality of the Si single crystal 17 is the amount of precipitated oxygen inside the wafer after the heat treatment (evaluation item (2)). Since this precipitated oxygen causes a gettering action, the amount of precipitation is It can be said that the one with a lot of is excellent. In order to increase the amount of precipitated oxygen, when the Si single crystal 17 is grown, the temperature range from 800 ° C. to 600 ° C. is gradually cooled at a cooling rate of 1.7 ° C./min or less (hereinafter referred to as slow cooling). It is known that you can pull it up.

Further, another item for evaluating the quality of the Si single crystal 17 is the oxide film breakdown voltage of the wafer (evaluation item (3)), but in order to increase the oxide film breakdown voltage when the Si single crystal 17 is grown. No useful technology has been developed so far.

In recent years, the control technology and the crystal growth technology have advanced, and the pulling has started to be carried out at a set predetermined speed.

[0008]

In the crystal growth apparatus and the crystal growth method shown in FIG. 4, the stacking fault related to the evaluation item (1) is suppressed, but all of the above three quality evaluation items are required. There was a problem that we could not deal with.

The present invention has been made in view of the above problems, and is based on the problems of oxidation-induced stacking fault (Oxidation induced Stac).
king Fault: hereinafter referred to as OSF) An object of the present invention is to provide a crystal growth apparatus and a crystal growth method capable of reducing the density, increasing the amount of precipitated oxygen inside the wafer after heat treatment, and improving the breakdown voltage of the oxide film on the wafer. I am trying.

[0010]

In order to achieve the above object, a crystal growth apparatus according to the present invention comprises a crucible filled with a raw material for crystal, a heater is provided around the crucible, and the crucible of the crucible is provided. In a crystal growth apparatus in which a pulling shaft is arranged above, at least three heating means and / or cooling means are arranged above the crucible along the pulling shaft ( 1).

In the crystal growth method according to the present invention, the single crystal is pulled at a predetermined rate by using the crystal growth apparatus described in (1) above, and the single crystal is subjected to at least three different cooling steps. It is characterized (2).

The crystal growth apparatus according to the present invention is the crystal growth apparatus according to the above (1), further comprising a measuring means for measuring the temperature of the single crystal and a control means for controlling the temperature of the heating means and / or the cooling means. It is characterized by being provided (3).

In the crystal growth method according to the present invention, the crystal growth apparatus described in (3) above is used to pull up a single crystal, and the control means is based on the temperature of the single crystal measured by the measurement means. Is operated, and at least three different cooling steps are applied to the single crystal (4).

[0014]

The present inventors have conducted research on the evaluation item (3) and have found that gradual cooling of the temperature range of 1420 to 1300 ° C. during crystal growth improves the oxide film breakdown voltage of the wafer.

The relationship between the cooling rate and the crystal quality for each temperature range in the crystal growth process is summarized in Table 1.

[0016]

[Table 1]

When the single crystal is stably pulled at a predetermined speed, the single crystal can be cooled at a predetermined speed by adjusting and setting the electric power required for heating and cooling, the supply amount of the cooling liquid, and the like. It will be.

According to the crystal growth apparatus of the above (1), since at least three heating means and / or cooling means are arranged above the crucible along the pulling axis, when pulling a single crystal. By previously setting the power addition patterns required for heating and cooling, the single crystal can be cooled at a predetermined cooling rate in at least three temperature ranges. Therefore, the quality of the single crystal is improved and the OS of the obtained wafer is
The F density can be reduced, the amount of precipitated oxygen inside the wafer after the heat treatment can be increased, and the oxide film withstand voltage can be improved.

According to the crystal growth method of the above (2),
Since the single crystal is pulled at a predetermined rate using the crystal growth apparatus of the above (1) and at least three different cooling steps are applied to the single crystal, the single crystal is cooled at a predetermined cooling rate in at least three temperature ranges. Since the single crystal can be cooled, therefore, the quality of the single crystal is improved, and the same effect as in the case (1) above can be obtained for the obtained wafer.

Further, in the crystal growth apparatus of the above (1),
When the measuring means for measuring the temperature of the single crystal and the control means for controlling the temperature of the heating means and / or the cooling means are provided, when pulling the single crystal, the temperature of the single crystal at each stage is adjusted to Based on this, the temperature of the heating means and / or the cooling means can be automatically controlled, and in at least three more accurate temperature ranges,
The single crystal can be surely cooled at each predetermined cooling rate, and therefore the quality of the single crystal can be further improved. Further, since the cooling rate is automatically controlled, it is possible to easily deal with the case where the pulling rate of the single crystal is changed.

According to the crystal growth method of the above (4),
The single crystal is pulled up using the crystal growth apparatus of the above (3), the control means is operated based on the temperature of the single crystal measured by the measuring means, and the single crystal is cooled in at least three different stages. Since the process is added, the single crystal can be surely cooled at a predetermined cooling rate in at least three more accurate temperature ranges, and therefore the quality of the single crystal can be further enhanced. Further, since the cooling rate is automatically controlled, it is possible to cope with the case where the pulling rate of the single crystal is changed.

[0022]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of a crystal growth apparatus and a crystal growth method according to the present invention will be described below with reference to the drawings.
It should be noted that components having the same functions as those of the conventional example are designated by the same reference numerals. FIG. 1 is an enlarged cross-sectional view schematically showing heating / cooling means of a crystal growth apparatus according to an embodiment,
In the figure, 13 indicates a crucible. The crucible 13 is formed in a substantially cylindrical shape with a bottom. A heater 14 is concentrically arranged on the outer periphery of the crucible 13. The crucible 13 is melted by the heater 14 to melt a raw material for Si crystal. 15 are filled. A pull-up shaft 16 is arranged on the central axis of the crucible 13, and heaters 21 a, 2 are arranged along the pull-up shaft 16.
2a, a cooling cylinder 23a, and a heater 24a are sequentially arranged. Power supplies P1, P2, P4 as heating power are connected to the heaters 21a, 22a, 24a, respectively, and a cooling liquid supply pump is connected to the flow chamber 23b of the cooling cylinder 23a via an introduction pipe / discharge pipe (both not shown). P3 is connected, heaters 21a, 22a, 24a and power supplies P1, P2,
The heating means 21, 22, and 24 are configured by P4, respectively, and the cooling means 23 is configured by the cooling cylinder 23a and the cooling liquid supply pump P3. Then, the heaters 21a, 22a, 24a are heated to a predetermined temperature by the electric power from the power sources P1, P2, P4, and the cooling liquid supply pump P3 circulates the cooling liquid in the circulation chamber 23b to cool the cooling cylinder 23a to the predetermined temperature. . Further, by contacting the seed crystal 16a with the surface of the melt 15 and pulling up the Si single crystal 17 formed by solidification of the melt 15 at a predetermined speed, 1420 to 1300
The Si single crystal 17 is cooled at different cooling rates, such as slow cooling in the temperature range of 0 ° C., rapid cooling in the temperature range of 1100 to 800 ° C., and slow cooling in the temperature range of 800 to 600 ° C. Since other configurations are similar to those of the conventional device, detailed description thereof will be omitted here.

As is clear from the above description, in the crystal growth apparatus according to the embodiment, the pulling shaft 1 is provided above the crucible 13.
Since the heating means 21 and 22, the cooling means 23, and the heating means 24 are arranged along the line 6, the power P1, P2, P required for heating and cooling when pulling up the Si single crystal 17 is provided.
By previously setting the additional patterns of 3 and P4 respectively, the Si single crystal 17 can be cooled at a predetermined cooling rate in each of the four temperature ranges. Therefore, the quality of the Si single crystal 17 can be improved, the OSF density of the obtained wafer can be reduced, the amount of precipitated oxygen in the wafer after the heat treatment can be increased, and the oxide film withstand voltage can be improved.

Further, in the crystal growth method according to the embodiment, the Si single crystal 17 is pulled at a predetermined speed by using the crystal growth apparatus of the embodiment, and the Si single crystal 17 is provided with four different cooling steps. It is possible to cool the Si single crystal 17 at a predetermined cooling rate in each of the step temperature ranges,
Therefore, the quality of the Si single crystal 17 can be improved.

FIG. 2 is an enlarged cross-sectional view schematically showing the heating / cooling means of the crystal growth apparatus according to another embodiment. In the figure, 21, 22 and 24 are heating means, and 23 is cooling. It shows the means. Heating means 21 and 22, cooling means 2
3. The heating means 24 is constructed and arranged similarly to that of the embodiment shown in FIG. 1, and each of them has a PID (Pr
The control means C1, C2, C3, C4 composed of an operational integral derivation) controller or the like are connected. Further, the height from the surface of the melt 15 is L ₁ , L ₂
, L _3, and the point of L _4, the temperature measuring means radiometer or the like for measuring the temperature of the Si single crystal 17 B1, B2, B3, B4
Are provided, which are control means C1, C2, C
3 and C4, respectively. Then, the temperatures of the heating means 21, 22, the cooling means 23, and the heating means 24 are adjusted by the control means C1, C2, C3, C4 based on the temperature data signals measured using the temperature measuring means B1, B2, B3, B4. ·Control. Further, the seed crystal 16a is brought into contact with the surface of the melt 15 to solidify the melt 15 to form S.
By pulling the i single crystal 17 at a predetermined speed,
The Si single crystal 17 is cooled at different cooling rates, such as slow cooling at 20 to 1300 ° C., rapid cooling at 1100 to 800 ° C., and slow cooling at 800 to 600 ° C.
The other structure is the same as that of the apparatus of the embodiment shown in FIG. 1, and therefore its detailed description is omitted here.

The results of measuring the crystal quality by pulling up a Si single crystal having a diameter of about 6 inches using the apparatus thus constructed will be described. The measurement and pulling conditions are shown in Tables 2 and 3, and the crystal quality measurement results are shown in Table 4. As a comparative example, the conventional apparatus shown in FIG. 3 was used, and the same measurement was performed using a single crystal grown without controlling the cooling rate.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

[Table 4]

As is clear from Table 4 above, in the case of the example, the crystal quality could be improved in all of the evaluation items 1, 2 and 3 as compared with the case of the comparative example.

Further, in the conventional apparatus shown in FIG. 4, when the crystal raw material filled in the crucible 13 is melted by using the heater 14, the crucible 13 and the crystal raw material are cooled by radiation of the cooling cylinder 31 or the like. Therefore, there is a problem that it takes a long time for melting. In the crystal growth apparatus according to the present embodiment, the cooling means 23
Since the heating means 21 and 22 are provided between the crucible 13 and the crucible 13, the crucible 13 and the crystal raw material can be prevented from being cooled by the cooling means 23, and the melting time can be shortened.

As is clear from these results, in the crystal growth apparatus according to this example, measuring means B1, B2, B3, B4 for measuring the single crystal temperature and heating means 21, 2 were used.
2, control means C1, C2, C3, C4 for controlling the temperatures of the cooling means 23 and the heating means 24 are provided, and Si
When pulling the single crystal 17, the temperatures of the heating means 21 and 22, the cooling means 23, and the heating means 24 can be automatically controlled based on the temperature of the Si single crystal 17 at each stage, and the four-stage more accurate In the temperature range, the Si single crystal 17 can be surely cooled at a predetermined cooling rate, so that the quality of the Si single crystal 17 can be further improved. Further, since the cooling rate can be automatically controlled, it is possible to cope with the case where the pulling rate of the Si single crystal 17 is changed.

In the crystal growth method according to this embodiment, the Si single crystal 17 is pulled up using the crystal growth apparatus shown in FIG. 2, and the Si single crystal measured by the measuring means B1, B2, B3 and B4. Control means C1, C based on the temperature of 17
2, C3, C4 are activated to give the Si single crystal 17 four different cooling steps, so that the Si single crystal 17 is reliably cooled at a predetermined cooling rate in each of the four more accurate temperature ranges.
The single crystal 17 can be cooled, and thus the quality of the Si single crystal 17 can be further improved. Further, since the cooling rate can be automatically controlled, it is possible to easily cope with the case where the pulling rate of the Si single crystal 17 is changed.

Further, in the embodiment, the case of applying to the CZ method has been described, but in another embodiment, it can be applied to the melt layer method and the like.

Further, although the case of growing a Si single crystal has been described in the embodiment, it can be applied to the pulling of germanium or the like in another embodiment.

[0036]

As described in detail above, in the crystal growth apparatus (1) according to the present invention, at least three heating means and / or cooling means are arranged above the crucible along the pulling axis. When the single crystal is pulled up, the additional patterns of power required for heating and cooling are set in advance so that the single crystal is cooled at a predetermined cooling rate in at least three temperature ranges. be able to. Therefore, the quality of the single crystal can be improved, the OSF density of the obtained wafer can be reduced, the amount of oxygen precipitated in the wafer after the heat treatment can be increased, and the withstand voltage of the oxide film can be improved.

In the crystal growth method (2) according to the present invention, the single crystal is pulled at a predetermined speed by using the crystal growth apparatus described in (1) above, and the single crystal has at least three different stages. Since the cooling step is provided, the single crystal can be cooled at a predetermined cooling rate in each of the temperature ranges of at least three stages, and thus the quality of the single crystal can be improved. The same effect as in the case of 1) can be obtained.

Further, in the crystal growth apparatus of the above (1), measuring means for measuring the single crystal temperature, heating means and / or
Alternatively, when a control means for controlling the temperature of the cooling means is provided, when pulling the single crystal, the heating means and / or the heating means based on the temperature of the single crystal in each stage are used.
Alternatively, the temperature of the cooling means can be automatically controlled, and in at least three more accurate temperature ranges,
The single crystal can be surely cooled at each predetermined cooling rate, and therefore the quality of the single crystal can be further improved. Further, since the cooling rate can be automatically controlled, it is possible to easily cope with the case where the pulling rate of the single crystal is changed.

According to the crystal growth method of the above (4),
The single crystal is pulled up using the crystal growth apparatus of the above (3), the control means is operated based on the temperature of the single crystal measured by the measuring means, and the single crystal is cooled in at least three different stages. Since the process is added, the single crystal can be reliably cooled at a predetermined cooling rate in at least three more accurate temperature ranges,
Therefore, the quality of the single crystal can be further improved. Further, since the cooling rate can be automatically controlled, it is possible to cope with the case where the pulling rate of the single crystal is changed.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view schematically showing heating / cooling means of a crystal growth apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view schematically showing heating / cooling means of a crystal growth apparatus according to another embodiment.

FIG. 3 is a sectional view schematically showing a crystal growth apparatus used in a conventional CZ method.

FIG. 4 is a cross-sectional view schematically showing a conventional crystal growth apparatus configured to rapidly cool a Si single crystal during pulling.

[Explanation of symbols]

 13 Crucible 14 Heater 16 Lifting Shaft 21, 22, 24 Heating Means 23 Cooling Means B1, B2, B3, B4 Temperature Measuring Means C1, C2, C3, C4 Control Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Kashihara 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd.

Claims (4)

[Claims] 1. A crystal growth apparatus comprising a crucible filled with a raw material for crystallization, wherein a heater is arranged around the crucible, and a pulling shaft is arranged above the crucible, above the crucible. A crystal growth apparatus comprising at least three heating means and / or cooling means arranged along the pulling axis. 2. A single crystal is pulled at a predetermined speed by using the crystal growth apparatus according to claim 1, and at least 3 is added to the single crystal.
A crystal growth method characterized by applying cooling steps in different stages. 3. The crystal growth apparatus according to claim 1, further comprising a measuring means for measuring the temperature of the single crystal and a control means for controlling the temperature of the heating means and / or the cooling means. 4. A single crystal is pulled up by using the crystal growth apparatus according to claim 3, and the control means is operated based on the temperature of the single crystal measured by the measuring means, so that at least the single crystal is processed. A crystal growth method characterized by applying three different cooling steps.