JP2003086525A - Jig for heat treatment of silicon wafer and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a jig for heat treatment of a silicon wafer such as a wafer boat, a susceptor, a chuck, and a holder used in a high-temperature heat treatment step of 1000 ° C. or more, having excellent heat resistance, mechanical strength, toughness, and the like, and Another object of the present invention is to provide a jig for heat treatment of a silicon wafer capable of suppressing transfer of impurity metal contamination to a wafer to be processed. SOLUTION: The nitrogen concentration is 1 × 10 ^{13 to} 5 × 10 ¹⁵ a.
toms / cm ³ and oxygen concentration of 8 × 10 ¹⁷ to 2 ×
10 ¹⁸ was atoms / cm ^3, after processing the silicon single crystal grown by the Czochralski method to the shape of the heat treatment jig, jig for heat treatment of 600 to 1000
A silicon wafer heat treatment jig that has been heat-treated at 10 ° C. for 10 minutes to 24 hours is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for heat treatment of a silicon wafer and a method for manufacturing the same, and more specifically,
The present invention relates to a silicon wafer heat treatment jig such as a wafer boat, a susceptor, a chuck, and a holder used for mounting a silicon wafer to be subjected to high temperature heat treatment, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a silicon wafer is subjected to various heat treatments such as diffusion, oxidation and CVD film formation. In these heat treatment steps, various jigs are used depending on the mode of each treatment, the type of heating means used, and the like. For example, in a heat treatment process using a vertical heat treatment furnace, a plurality of silicon wafers are loaded into a holding jig, a so-called vertical wafer boat, to process the wafers in multiple vertical stages.

In this vertical wafer boat, a plurality of (four in FIG. 2) columns 3 are provided between an upper plate 1 and a lower plate 2, as shown in FIG. The pillar 3 has a structure in which a large number of grooves (slits) 4 for supporting the wafer 5 to be processed are provided. The wafer 5 to be processed is supported at a plurality of locations (4 locations in FIG. 2) on the outer peripheral portion of the wafer by the grooves 4 of the support column 3 and horizontally placed in the vertical wafer boat at equal intervals. Heat treatment is applied. As the constituent material of this vertical wafer boat, generally, single crystal silicon, polycrystalline silicon, quartz glass,
A silicon carbide material or the like is used.

Further, in the case of thin film vapor phase growth processing on a wafer surface by an epitaxial growth apparatus or the like, for example, a batch type consisting of quartz glass, single crystal silicon, polycrystalline silicon, a graphite base material coated with silicon carbide or the like is used. A silicon wafer is placed on a single-wafer type susceptor, and heat treatment is performed.

[0005]

However, when the constituent material of the jig for heat treatment of silicon wafers such as the vertical wafer boat and the susceptor is quartz glass, it is easily deformed at a high temperature and heat treatment at a high temperature exceeding 1000 ° C. is required. Can not be used. Further, in the heat treatment under an atmosphere containing a reducing gas such as hydrogen gas, the silicon carbide material is
It reacts with hydrogen and causes the generation of particles and contamination transfer of impurity metal on the wafer, which makes it unusable.

Therefore, the constituent material of the silicon wafer heat treatment jig, such as a wafer boat, used in the high temperature heat treatment step at 1000 ° C. or higher is conventionally known from the viewpoints of heat resistance and prevention of contamination by particles and the like. A silicon single crystal by the Czochralski (CZ) method or the floating zone (FZ) method or a polycrystalline silicon by the vapor phase chemical growth (CVD) method, which is the same material as the silicon wafer to be processed, has been widely used.

However, although the silicon material obtained by the CZ method or the like has high purity, it is not always sufficient in strength and is brittle, so that a silicon material having higher strength and excellent toughness is required. Regarding this point, for example, in Japanese Patent No. 3117573, a silicon melt containing nitrogen atoms at a concentration of 10 ¹⁶ atoms / cm ³ or more is solidified to form fibrous silicon nitride. It has been proposed to improve the bending strength and fracture toughness of silicon materials by using silicon fiber reinforced silicon materials.

On the other hand, the impurity metal contamination of the wafer to be processed in the heat treatment step of the silicon wafer as described above is L
It is one of the main factors that deteriorate the electrical characteristics of SI,
This preventive measure is also an important issue because it may cause deterioration of the oxidation resistance of the wafer and defective junction leakage. further,
In recent years, with the miniaturization and high integration of LSI, the permissible level for impurity metal contamination of wafers is becoming more and more
The demands are becoming stricter.

Therefore, in order to prevent transfer of impurity metal contamination from a heat treatment jig such as a wafer boat or a susceptor that comes into direct contact with a silicon wafer in the heat treatment step, the surface of the heat treatment jig contains an impurity metal. Concentration
There is a strong demand for reduction to the same level as the silicon wafer to be processed.

However, in the conventional heat treatment jig, although there are some differences depending on the type, material, etc., a considerable amount of impurity metal remains on the surface layer of the heat treatment jig. There is. Even in the heat treatment jig made of the silicon material in which the above-mentioned fibrous silicon nitride is deposited, the gettering ability in the bulk of the silicon material is not sufficient,
It has not been possible to sufficiently prevent transfer of impurity metal contamination from the heat treatment jig.

The present invention has been made to solve the above technical problems, and relates to a silicon wafer heat treatment jig such as a wafer boat, a susceptor, a chuck, and a holder used in a high temperature heat treatment process at 1000 ° C. or higher.
It is an object of the present invention to provide a jig for heat treatment of a silicon wafer, which is excellent in heat resistance, mechanical strength, toughness, etc., and can suppress transfer of impurity metal contamination to a wafer to be processed, and a manufacturing method thereof. is there.

[0012]

A jig for heat treatment of a silicon wafer according to the present invention is a jig for heat treatment of a silicon wafer used in a high temperature heat treatment step of 1000 ° C. or higher, and has a nitrogen concentration of 1 × 10 ¹³ to. 5 × 10 ¹⁵ atoms /
cm ³ , and oxygen concentration is 8 × 10 ¹⁷ to 2 × 10 ¹⁸ at
oms / cm ³ and is characterized by being composed of a silicon single crystal grown by the Czochralski method. This heat treatment jig has a low impurity metal concentration in its surface layer, can prevent transfer of impurity metal contamination to the wafer to be processed, and is excellent in heat resistance, mechanical strength, toughness, etc. Is.

The heat treatment jig is preferably a wafer boat, a susceptor, a chuck, or a holder. Since the heat treatment jig according to the present invention is excellent in heat resistance, mechanical strength, toughness, etc. as described above, in particular, a jig for mounting a silicon wafer such as a wafer boat, a susceptor, a chuck, a holder, etc. It can be suitably used as a tool.

The method for manufacturing a jig for heat treatment of a silicon wafer according to the present invention is the method for manufacturing a jig for heat treatment of a silicon wafer used in a high temperature heat treatment step of 1000 ° C. or higher, wherein the nitrogen concentration is 1 × 10 ¹³ to 5 x 10 ¹⁵ a
toms / cm ³ , and oxygen concentration is 8 × 10 ¹⁷ to 2 ×
10 ¹⁸ atoms / cm ³ , and the silicon single crystal grown by the Czochralski method was processed into the shape of the heat treatment jig, and then the heat treatment jig was adjusted to 600 to 1000.
It is characterized in that it is heat-treated at a temperature of 10 minutes to 24 hours. By performing the heat treatment on the jig for heat treatment of nitrogen concentration and oxygen concentration, nuclei of oxygen precipitates can be formed at high density in the silicon single crystal, whereby the surface layer portion of the jig is formed. Since it is possible to trap the impurity metal, the transfer of the impurity metal contamination to the silicon wafer is suppressed.

The heat treatment at 600 to 1000 ° C. is at least 1 selected from oxygen, nitrogen, hydrogen and argon.
It is preferable to be carried out under a seed gas atmosphere. By performing the heat treatment under these gas atmospheres, the surface layer portion of the heat treatment jig can be made smoother and the surface layer portion can be made defect-free.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The silicon wafer heat treatment jig according to the present invention has a nitrogen concentration of 1 × 10 ^{13 to} 5 × 10 ¹⁵ as its constituent material.
atoms / cm ³ , and oxygen concentration is 8 × 10 ¹⁷ to 2
A silicon single crystal grown by the Czochralski (CZ) method with a density of × 10 ¹⁸ atoms / cm ³ is used. The silicon single crystal may be appropriately manufactured depending on the type, shape, etc. of the heat treatment jig to be manufactured. Generally, the CZ high-purity silicon single crystal is industrially produced as an ingot with a diameter of 300 mm and a straight body length of about 1.2 m as a material for manufacturing a silicon wafer, and is commercially available. , This can be used.

In the CZ method silicon single crystal, the interstitial oxygen concentration is generally in a supersaturated state, and upon receiving a thermal history, the interstitial oxygen reacts with Si to form an oxide such as SiO ₂ . At this time, excess Si is released as interstitial Si due to volume expansion and the like, and secondary defects such as dislocations are formed in the single crystal.

Such precipitates due to interstitial oxygen are called bulk microdefects (BMD),
It becomes a gettering source of impurity metals. The type and production density of this BMD are greatly influenced by the oxygen concentration in the single crystal, the dopant (for example, nitrogen atom) concentration, the precipitation nuclei introduced during the growth of the single crystal, the heat treatment conditions when the BMD is formed, and the like. It is known that The BMD state also affects the strength characteristics of the single crystal, and the mechanical strength increases when the oxygen concentration in the silicon single crystal is appropriate.

Further, in the heat treatment jig according to the present invention, the nitrogen concentration in the silicon single crystal which is the constituent material is 1 × 1.
It is characterized in that the oxygen concentration is 0 ^{13 to} 5 × 10 ¹⁵ atoms / cm ³ and the oxygen concentration is 8 × 10 ¹⁷ to 2 × 10 ¹⁸ atoms / cm ³ . The CZ method silicon single crystal having a nitrogen concentration in the above range does not deposit silicon nitride in the single crystal and inhibits the formation of a high-density oxygen precipitate (BMD), which is an oxidation-induced stacking fault (OSF). ; Oxidation induced
Stacking Fault) is in the area where it does not occur (low density area). Therefore, a jig manufactured by processing a CZ method silicon single crystal having a nitrogen concentration and an oxygen concentration in the above-mentioned range that does not inhibit the generation of oxygen precipitates, even when used in a high temperature heat treatment step, Sufficient density of gettering sites are generated in the bulk. In addition, the degree of crystal distortion is appropriate, and since the crystal distortion and impurities are small in the surface layer portion due to the action of the dopant (nitrogen), it can be suitably used as a jig for heat treatment of a silicon wafer.

The nitrogen concentration in the silicon single crystal, which is the constituent material of the heat treatment jig according to the present invention, is 1 × 10 ¹³ atom.
When it is less than s / cm ³ , even if the oxygen concentration is within the above range, the effect of promoting the nucleation of oxygen precipitates during heat treatment is small, and the gettering effect cannot be improved. On the other hand, the nitrogen concentration is 5 × 10 ¹⁵ atoms
If it exceeds / cm ³ , silicon nitride will be precipitated in the silicon single crystal, and the concentration range will be where OSF is generated.
The production density of oxygen precipitates decreases, and in this case also, the gettering effect decreases.

If the oxygen concentration in the silicon single crystal is less than 8 × 10 ¹⁷ , the gettering effect is insufficient and sufficient mechanical strength cannot be obtained. On the other hand, when the oxygen concentration exceeds 2 × 10 ¹⁸ atoms / cm ³ , growth stripes appear and BMD generation is non-uniform.

The oxygen concentration in the silicon single crystal is CZ.
When pulling a single crystal by the method, it can be controlled as follows. In the CZ method, since the raw material silicon is melted using a quartz crucible, quartz (SiO ₂ ) is dissolved in the melt, whereby oxygen is introduced as an impurity into the melt and convection occurs. About 90% or more of the oxygen introduced into the melt as described above evaporates as SiO from the surface of the melt, but a part of the oxygen is guided to just below the solid-liquid interface and taken into the silicon single crystal. . as mentioned above,
The oxygen concentration in the silicon single crystal depends on the melting amount of the quartz crucible and the evaporation amount from the silicon melt surface. It depends on the free surface area of the liquid (that is, the ratio of the diameter of the quartz crucible and the diameter of the silicon single crystal) and the like, and the concentration can be controlled by controlling these parameters.

In the CZ method silicon crystal, among impurities,
Generally, oxygen is the most, and its concentration is usually 5 × 10 ¹⁷
In the concentration range of about 10 × 10 ¹⁷ atoms / cm ³ ,
It is controlled with an accuracy of ± 1 × 10 ¹⁷ or less. Therefore, the oxygen concentration range specified in the present invention is a range that can be easily controlled.

Next, as a method of introducing nitrogen having a concentration defined in the present invention into a silicon single crystal, for example,
A method of loading a predetermined amount of solid nitrogen source together with a silicon melt raw material such as high-purity polysilicon into a melting crucible in advance and heating and melting, and adding a predetermined amount of solid nitrogen source to the silicon melt raw material afterwards. And the like, and a method of introducing a nitrogen-containing gas such as nitrogen gas, ammonia gas, or nitrogen oxide into the silicon melt.

Further, the jig according to the present invention is, for example, a wafer boat or a susceptor by processing a silicon single crystal bulk such as an ingot into a predetermined shape by cutting, polishing or the like, and assembling the jig into a jig if necessary. , A chuck, a holder, etc. for a silicon wafer heat treatment jig.

Further, in the method for manufacturing a jig for heat treatment of a silicon wafer according to the present invention, the jig processed and assembled as described above is further subjected to 600 to 1000.
It is preferable to perform the heat treatment in the temperature range of ℃, more preferably 650 to 800 ℃. A jig obtained by processing single crystal silicon having the above nitrogen concentration and oxygen concentration is
By heat treatment at up to 1000 ° C., a large number of nuclei of oxygen precipitates (BMD) can be formed at high density in the silicon single crystal bulk forming the jig.

The nuclei of the oxygen precipitates can be obtained by using the jig in the high temperature heat treatment process of silicon wafers.
It grows and the size of oxygen precipitates increases. The larger the size and the higher the density, the greater the ability to capture the impurity metal in the bulk, that is, the gettering effect. Therefore, by heat treatment at 600 to 1000 ° C. to form nuclei of oxygen precipitates at a high density,
Impurity metals in the surface layer portion of the silicon single crystal bulk forming the jig can be trapped. Then, in the heat treatment process of the silicon wafer, it is possible to suppress the transfer of the impurity metal contamination from the jig used to the wafer.

The time for the heat treatment is appropriately set according to the size, shape, structure, etc. of the jig, but the jig is a jig for mounting a silicon wafer such as a wafer boat, a susceptor, a chuck, and a holder. In the case of a tool, it is usually set in the range of 10 minutes to 24 hours in order to uniformly form nuclei of oxygen precipitates in the silicon single crystal bulk constituting the jig.

In the present invention, the heat treatment of the jig is preferably performed in an atmosphere of at least one gas selected from oxygen, nitrogen, hydrogen and argon.
Therefore, the gas used may be any one of these gases or a mixed gas thereof. By performing the heat treatment in the gas atmosphere, the surface layer portion of the jig can be made smoother and defect-free can be achieved.

Since the heat treatment jig according to the present invention is made of the above-mentioned silicon single crystal, it is excellent in heat resistance, mechanical strength, toughness, etc.
It is suitable for a jig for mounting a wafer such as a wafer boat, a susceptor, a chuck and a holder used in a high temperature heat treatment step at 000 ° C or higher. In particular, it is useful for a wafer boat that has a relatively complicated structure and is unlikely to trap impurities in the surface layer by other manufacturing methods.

[0031]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by the following examples. Example 1 A CZ method silicon single crystal having a nitrogen concentration and an oxygen concentration as shown in Table 1 was processed into a vertical wafer boat as shown in FIG. 1 and then heat-treated at 650 ° C. for 12 hours. . A silicon wafer was loaded into this vertical wafer boat, and the wafer was heat-treated at 1200 ° C. in a hydrogen gas atmosphere. Regarding the silicon wafer after the heat treatment, the Fe concentration at the contact portion with the wafer boat was measured by the surface photovoltaic method (S
PV method). The results are shown in Table 1.

Example 2 A CZ method silicon single crystal having a nitrogen concentration and an oxygen concentration as shown in Table 1 was processed into a vertical wafer boat as shown in FIG.
Heat treatment was performed for 0 hours. A silicon wafer was loaded into this vertical wafer boat, and the wafer was heat-treated at 1200 ° C. in a hydrogen gas atmosphere. Then, the Fe concentration of this silicon wafer was measured in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 1 and 2] CZ method silicon single crystals having nitrogen concentration and oxygen concentration as shown in Table 1 are shown in FIG.
Processed into a vertical wafer boat as shown in FIG. Silicon wafers were loaded into these vertical wafer boats, and the wafers were heat-treated at 1200 ° C. in a hydrogen gas atmosphere.
The concentration was measured. The results are shown in Table 1.

[0034]

[Table 1]

As shown in Table 1, the nitrogen concentration is 1 × 1.
0¹³~ 5 x 10¹⁵atoms / cm ³And the oxygen concentration
Is 8 × 10¹⁷~ 2 x 10¹⁸atoms / cm³Is C
It is a vertical wafer boat made of Z method silicon single crystal.
Heat treatment at 600 to 1000 ° C for 10 minutes to 24 hours.
(Examples 1 and 2) used in the heat treatment process
Contamination transfer of impurity metal (Fe) to silicon wafers
It was confirmed that copying was suppressed.

[0036]

As described above, according to the present invention, a silicon wafer having excellent heat resistance at high temperature, mechanical strength, toughness, etc., and capable of suppressing transfer of impurity metal contamination to a wafer to be processed. A heat treatment jig can be provided.
The jig for heat treatment of a silicon wafer obtained by the present invention is
In particular, it can be suitably used for a jig for mounting a silicon wafer, such as a wafer boat, a susceptor, a chuck, and a holder.

[Brief description of drawings]

FIG. 1 is a perspective view showing a general vertical wafer boat.

[Explanation of symbols]

1 Upper plate 2 Lower plate 3 props 4 grooves (slits) 5 wafers

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/31 H01L 21/31 E (72) Inventor Koji Araki 6-861 East Port, Seiro Town, Kitakanbara-gun, Niigata Prefecture 5 Niigata Toshiba Ceramics Co., Ltd. (72) Inventor Toru Yamashita 6-861-5 East Port, Seiro-cho, Kitakanbara-gun, Niigata Prefecture F-term (reference) 4K030 CA04 CA12 GA02 KA46 LA15 5F045 AA03 AA20 BB14 BB15 BB20 DP19 DQ05 EM09

Claims (4)

[Claims] 1. A jig for heat treatment of a silicon wafer used in a high temperature heat treatment process at 1000 ° C. or higher, wherein the nitrogen concentration is 1 × 10 ^{13 to} 5 × 10 ¹⁵ atoms / cm 3.
³ and oxygen concentration is 8 × 10 ¹⁷ to 2 × 10 ¹⁸ atom
A jig for heat treatment of a silicon wafer, wherein the jig is s / cm ³ and is composed of a silicon single crystal grown by the Czochralski method. 2. The silicon wafer heat treatment jig according to claim 1, wherein the heat treatment jig is any one of a wafer boat, a susceptor, a chuck, and a holder. 3. A method of manufacturing a jig for heat treatment of a silicon wafer used in a high temperature heat treatment step at 1000 ° C. or higher, wherein the nitrogen concentration is 1 × 10 ^{13 to} 5 × 10 ¹⁵ atoms / cm 3.
³ and oxygen concentration is 8 × 10 ¹⁷ to 2 × 10 ¹⁸ atom
s / cm ³ , after processing a silicon single crystal grown by the Czochralski method into the shape of the heat treatment jig, the heat treatment jig is heated at 600 to 1000 ° C. for 10 minutes to 2
A method of manufacturing a jig for heat treatment of a silicon wafer, which comprises performing heat treatment for 4 hours. 4. The heat treatment at 600 to 1000 ° C.
4. The method for manufacturing a silicon wafer heat treatment jig according to claim 3, wherein the method is performed in an atmosphere of at least one gas selected from oxygen, nitrogen, hydrogen, and argon.