JPH10209064A - Wafer boat member for semiconductor heat treatment and wafer boat for semiconductor heat treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of slip of a wafer, suppress defective coloring of the wafer and prevent generation of particles within a furnace. SOLUTION: A wafer boat 1 is a so-called vertical wafer boat in which four pole support members 2 are arranged in parallel with each other by a pair of upper plate 3 and lower plate 4. Each support member 2 is provided with a plurality of slits 2a with the predetermined interval in order to load semiconductor wafers. Material at least to form the support member 2 is glass carbon material and this glass carbon material has the porous coefficient ratio of 0.2% or less and the surface roughness of the support member 2 is set to 0.5 to 1.5μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment wafer boat member and a semiconductor heat treatment wafer boat in which a plurality of slits are formed at predetermined intervals in a support member for loading a plurality of semiconductor wafers. In particular, the present invention relates to a semiconductor heat treatment wafer boat member and a semiconductor heat treatment wafer boat formed of a glassy carbon material.

[0002]

2. Description of the Related Art In a semiconductor wafer annealing process or a CVD process for forming an epi layer, an insulating film, and a polysilicon film, a large number of semiconductor wafers are loaded on a wafer boat,
The wafer boat is carried into the high-temperature furnace or the reaction tube as it is, and a desired process is performed. In this case, a so-called vertical boat or a horizontal boat is used depending on the type of the high-temperature furnace or the reaction tube.

In order to support a plurality of wafers in a horizontal or slightly inclined state, the vertical boat includes a plurality of (for example, four) rod-shaped support members each of which is composed of a pair of an upper plate and a lower plate. The plurality of slits provided in the support members are arranged in parallel in the longitudinal direction in parallel with each other by the shape members, and the semiconductor wafer is loaded on each of the plurality of slits. Further, in order to support the plurality of wafers vertically or slightly inclined, the horizontal boat is arranged such that a plurality of support members project parallel to each other with respect to the inner surface of the arc-shaped main body. The semiconductor wafer is loaded on each of the plurality of slits provided in the support member.

Incidentally, these conventional boats are made of silicon, quartz glass, silicon carbide, or the like, and the boats made of these materials have the following characteristics in a wafer annealing process and the like. have. That is, the silicon boat is 1100
Since it does not soften even at a high temperature of not less than ° C., and there is no problem in strength reduction, it has an advantage that a large-diameter wafer of 8 inches or more can be mounted, for example, 100 or more wafers can be mounted at the same time. In addition, it has the advantage that the delamination phenomenon called flaking, which is seen in a quartz glass boat, does not occur.

On the other hand, since silicon boats are extremely difficult to weld with silicon, the support rods (or rods), side frames (or side plates), and wedges must be individually prepared and assembled. There is a drawback in that so-called misalignment or backlash occurs between the members, resulting in poor positional accuracy. Also,
Since it is slightly corroded by acid cleaning after annealing,
Each time washing is repeated, the amount of corrosion increases, and the above-described assembly accuracy is further reduced. Further, although the same material as the wafer is used, when the boat is formed, the thickness becomes large, and the stress is exerted on the wafer at the contact point with the wafer.

In addition, the quartz glass boat has an advantage that the quartz glass is softened at a high temperature and is deformed before the wafer at the contact portion between the wafer and the boat, so that the slip generated on the wafer is small. However, there is a drawback that a strain point exists at about 1100 ° C., and at a temperature higher than 1100 ° C., the material softens and causes plastic deformation even under its own weight. In particular, in the case of argon annealing or hydrogen annealing, since heating is generally performed at 1200 ° C. or higher, the quartz glass boat has a disadvantage that its life is short. At a temperature of 1000 ° C. or higher, there is a disadvantage that devitrification occurs and peeling called flaking occurs to generate particles in the furnace.

Further, a silicon carbide boat has the advantage of maintaining high strength even at a high temperature of 1200 ° C. or higher and not being deformed, but has a high hardness and does not soften even at a high temperature (the hardness does not decrease). In addition, there is a disadvantage in that the wafer is likely to slip on the point of supporting the wafer.
At a high temperature, the strength of the wafer is reduced, but silicon carbide is hard and has a high strength, so that there is a disadvantage that stress adversely affects the wafer.

As described above, a conventional boat made of silicon, quartz glass, silicon carbide, or the like has advantages, but has the above-mentioned disadvantages. These drawbacks are due to the intrinsic properties of the material,
A boat member using a glassy carbon material has been newly proposed. (JP-A-6-39356).

[0009]

When this glassy carbon material is used as a wafer boat, it does not soften even at a high temperature of 1100 ° C. or more, and the peeling of a formed film as seen in a quartz glass wafer boat is small. And the generation of particles is small. Further, since the hardness is lower than that of silicon and silicon carbide, and further lower than that of quartz glass, there is an advantage that a slip does not easily occur on the wafer. However, even in the case of a wafer boat made of a glassy carbon material, peeling of the generated film occurs, and particles are generated. As a result, there has been a technical problem that the occurrence of slip with respect to the wafer cannot be completely suppressed, and a so-called stain spot is formed on the wafer after the heat treatment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems of the prior art, and is intended to provide a wafer boat member and a wafer boat made of glassy carbon material.
An object of the present invention is to provide a semiconductor heat treatment wafer boat member and a semiconductor heat treatment wafer boat that can suppress the occurrence of slip on the wafer and prevent the occurrence of contamination such as irregular coloring spots on the wafer. It is.

[0011]

A wafer boat member for semiconductor heat treatment according to the present invention, which has been made to achieve the above object, is a glassy carbon material having a porosity of 0.2% or less, and has a surface roughness of 0.2% or less. It is characterized in that Ra is 0.5 to 1.5 μm.

According to another aspect of the present invention, there is provided a wafer boat for semiconductor heat treatment, wherein a plurality of slits for loading semiconductor wafers are formed on a plurality of support members at predetermined intervals. A wafer boat for semiconductor heat treatment, wherein at least the support member is made of a glassy carbon material having a porosity of 0.2% or less, and the support member has a surface roughness Ra of 0.5 to 1.5 μm. It is characterized by being.

In this case, in the wafer boat for semiconductor heat treatment according to the present invention, preferably, the plurality of supporting members are arranged in parallel with each other by a pair of upper plate-shaped member and lower plate-shaped member. A vertical wafer boat in which a plurality of slits for loading semiconductor wafers are formed at predetermined intervals, wherein the supporting member, the upper plate and the lower plate are glass-like having a porosity of 0.2% or less. A carbon material and have a surface roughness Ra of 0.5 to 1.5
μm is desirable.

In the wafer boat for semiconductor heat treatment according to the present invention, preferably, the plurality of support members are arranged so as to protrude in parallel with each other with respect to the inner surface of the arc-shaped main body. A horizontal wafer boat in which a plurality of slits for loading wafers are formed at predetermined intervals, wherein the support member and the arc-shaped main body have a porosity of 0.
It is desirable that they are made of a glassy carbon material of 2% or less and that their surface roughness Ra is 0.5 to 1.5 μm.

Since the material of the wafer boat member for semiconductor heat treatment constituted as described above, or at least the support member constituting the wafer boat for semiconductor heat treatment is made of a glassy carbon material, as shown in Table 1, Hardness (Vickers hardness) is significantly lower than silicon, quartz glass or silicon carbide used in conventional boats. The values in Table 1 are based on original measurements.

[0016]

[Table 1]

Similarly, since the hardness of glassy carbon is much lower than that of a wafer, when a vertical boat or a horizontal boat is formed and heat-treated by mounting a wafer,
Slip generated on the wafer can be significantly suppressed.

Further, since at least the supporting member is made of a glassy carbon material having a porosity of 0.2% or less,
The gas adsorbed on the glassy carbon material is not released, so that the wafer is not stained during the subsequent heat treatment, and the occurrence of contamination such as irregular colored spots on the wafer can be prevented. Further, since the surface roughness Ra of the slit formed in the support member is formed in the range of 0.5 to 1.5 μm, peeling of the generated film does not occur as in the case of quartz glass. The generation of particles in the furnace is reduced as compared with the above boat.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wafer boat for semiconductor heat treatment according to the present invention will be described in detail based on an embodiment shown in the drawings. First, FIG. 1 shows a first embodiment of a wafer boat for semiconductor heat treatment. This wafer boat 1 is a so-called vertical wafer boat,
The columnar support members 2 are arranged in parallel with each other by a pair of upper plate-like members 3 and lower plate-like members 4.
Each support member 2 has a plurality of slits 2a for loading semiconductor wafers at predetermined intervals.
An annular recess 4b is formed at the center of the lower surface 4a of the lower plate-like body 4 and a positioning hole 4c is formed at the center of the recess 4b. The wafer boat 1 can be integrally attached to the elevating table by positioning pins formed on the elevating table (not shown) using the holes 4c.

FIG. 2 shows a second embodiment of a wafer boat for semiconductor heat treatment. This wafer boat 11 is a so-called horizontal wafer boat, and FIG.
As shown in FIG. 2A and FIG. 2B, four support members 13 are integrally arranged on the inner surface of the boat body 12 formed in an arc shape so as to protrude in parallel with each other. In the member 13, a plurality of slits 13a for loading the semiconductor wafer W are formed at predetermined intervals. The horizontal wafer boat 11 is formed by, for example, forming a support member 13 on the inner surface of a cylindrical body (not shown) so as to protrude, and dividing the cylindrical body into three in the axial direction. FIG. 2 (C) shows a boat 1 in which a hollow portion 12a is formed at a position avoiding the support member 13 in the boat body 12.
1 to reduce the heat capacity.

The vertical boat shown in FIGS.
The horizontal boat is a glassy carbon material having a porosity of 0.2% or less, and has a surface roughness Ra of 0.5 to 1.5 μm, a support member 2, an upper plate member 3, and a lower plate member. It is constituted by the body 4, the boat body 12, and the support member 13.

[0022]

EXAMPLES Next, in the form of each of the wafer boats shown in FIGS. 1 and 2, a comparison was made of various characteristics when formed based on each material. (Example 1) Vertical boats having the shape shown in FIG. 1 were prepared from the following materials. (A) single crystal silicon (b) quartz glass (c) silicon carbide (d) glassy carbon

After the boats of the materials shown in (a) to (d) are dried and washed in a HCl + O ₂ gas at 1250 ° C. for 20 hours, an 8-inch wafer is mounted and annealed in an argon atmosphere at 1200 ° C. for 1 hour. Processing was performed. After this heat treatment process, the number of slips generated on the wafer was measured.
Table 2 shows the results. The slip line in Table 2 is
The number of slips generated per one 8-inch wafer is shown.

[0024]

[Table 2]

As described above, as shown in Table 2, slip lines were observed in the single crystal silicon boat and the silicon carbide boat. No slip line was observed in the quartz glass boat and the glassy carbon boat. However, in this comparative experiment, the quartz glass boat of (b) was devitrified during dry cleaning and deformed, and had to be discarded after being used once. Table 2 shows the same performance as glassy carbon, but it was found that it was difficult to use a quartz glass boat in the annealing process.

Example 2 The horizontal boat shown in FIG. 2 was made of glassy carbon having a different porosity, and the number of defective wafers after the heat treatment was compared. Here, the porosity of the glassy carbon was changed in the range of 0.02% to 1.5% as shown in Table 3. The horizontal boat was set at 1250 ° C and HCl +
After drying and cleaning in O ₂ gas for 5 hours, 10 hours, and 20 hours, 10 8-inch wafers were mounted and 120
Anneal for 1 hour in an argon atmosphere at 0 ° C.
After the processing, the number of defective sheets was measured. In this boat, up to 20 wafers can be installed, but 10 wafers were installed in every other groove, and the number of defective wafers among the 10 wafers was measured. Table 3 shows the results.

[0027]

[Table 3]

As shown in Table 3 above, a porosity of 0.8 to
The wafer heat-treated with a boat having 1.5% and a drying time of 10 hours or less has colored spots such as spots (shape, shading,
(Coloring irregular in size) was observed. It has been impossible to form an LSI through such a defective wafer through a semiconductor manufacturing process. On the other hand, when the porosity was 0.4 or less, no colored spots such as spots were observed on the heat-treated wafer even when the boat was dried for 5 hours.

[0029] The colored spots which cause the defect are as follows.
Gases including hydrogen are easily adsorbed to glassy carbon with high porosity, and it is presumed that this is released during heat treatment and contaminates the inside of the furnace and the wafer, so the relationship between porosity and gas release amount, and The released gas was analyzed. First, in order to remove contaminants attached to the boat, in particular, metals, the boat is immersed in a hydrofluoric acid solution or a mixed acid solution of hydrofluoric acid and nitric acid, and wet-cleaned.
It was heated to 0 ° C. for several hours and dried sufficiently. And 10
^-9 Torr, 100 when held at 900 ° C for 1 hour
The amount of gas released per gram was determined by volume under standard conditions. The released gas was subjected to mass spectrometry.

As a result, it became clear that the released gases were hydrogen and carbon monoxide. It was found that moisture penetrated the pores of the glassy carbon and was released as hydrogen and carbon monoxide during the subsequent high-temperature holding process. Further, as shown in FIG. 3, the relationship between the porosity and the gas release amount is 0.5 ml / 100 g if the porosity is 0.2% or less, but it is found that the porosity and the gas release amount further increase when the porosity is more than 0.2%. did. This tendency of the gas release amount with respect to the porosity corresponds to the number of defective wafers shown in Table 3. That is, if the porosity is 0.2% or less, this is consistent with the fact that even if the dry cleaning time is short, defective products are reduced. Therefore, it is desirable that the wafer boat for semiconductor heat treatment be made of a glassy carbon material having a porosity of 0.2% or less.

In the CVD process, a nitride film, an oxide film, and a silicon film adhere to the above-mentioned glassy carbon boat, and these films are peeled off by repeated use, causing particles in the furnace. Therefore, the surface roughness Ra of the glassy carbon boat was adjusted to verify the effect of preventing film peeling. The CVD process in the semiconductor process includes a film forming process as shown in Table 4 below.

[0032]

[Table 4]

(Example 3) A vertical glassy carbon boat having a surface roughness Ra changed as shown in Table 5 was subjected to pressure reduction CV.
In the oxide film forming step using the D apparatus, the separation of the oxide film adhered to the glassy carbon boat was examined, and the number of particles generated in the furnace was measured. The conditions of the test process in this case are as shown in the case of the oxide film in Table 4 above. The generated oxide film was SiO ₂ and was formed to a thickness of 0.15 μm in one process.

[0034]

[Table 5]

As is apparent from the above results, it was recognized that the oxide film adhered to the glassy carbon boat did not peel off when the surface roughness Ra was 0.5 to 1.5 μm. It was also found that the generation of particles at the surface was reduced. Therefore, as a wafer boat member for semiconductor heat treatment, a glassy carbon material having a porosity of 0.2% or less and having a surface roughness Ra of 0.5 to 1.5 μm is suitable. There was found.

[0036]

As is apparent from the above description, according to the semiconductor heat treatment wafer boat member and the semiconductor heat treatment wafer boat according to the present invention, a glassy carbon material having a porosity of 0.2% or less, Surface roughness Ra is 0.5-1.
Since the thickness is set to 5 μm, occurrence of slip on the wafer can be significantly reduced, and defective coloring of the wafer can be suppressed. Further, there is no separation as seen in quartz glass, and generation of particles in the furnace can be prevented.

The upper plate and the lower plate other than the support member in the vertical boat are also made of a glassy carbon material having a porosity of 0.2% or less and have a surface roughness Ra. Is set to 0.5 to 1.5 μm, the occurrence of slip can be further reduced and the coloring failure of the wafer can be suppressed as compared with the case where only the support member is used.
There is no separation as seen in quartz glass, and the generation of particles in the furnace can be further prevented.

Further, in the horizontal wafer boat, the arc-shaped main body other than the support member is also made of a glassy carbon material having a porosity of 0.2% or less and has a surface roughness Ra.
Is 0.5 to 1.5 μm, as in the case of the vertical boat, it is possible to further reduce the occurrence of slippage and to suppress defective coloring of the wafer, as compared with the case where only the support member is used. As a result, there is no separation as seen in quartz glass, and the generation of particles in the furnace can be further prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a wafer boat for semiconductor heat treatment according to the present invention.

FIG. 2 is a perspective view and a sectional view showing a second embodiment of the wafer boat for semiconductor heat treatment according to the present invention.

FIG. 3 is a characteristic diagram showing the relationship between the porosity of glassy carbon and the amount of released gas.

[Explanation of symbols]

 Reference Signs List 1 vertical wafer boat 2 support member 2a slit 3 upper plate 4 lower plate 4a lower surface 4b annular recess 4c positioning hole 11 horizontal wafer boat 12 boat body 12a cavity 13 support member 13a slit

Claims (4)

[Claims] 1. A wafer boat member for semiconductor heat treatment, which is a glassy carbon material having a porosity of 0.2% or less and has a surface roughness Ra of 0.5 to 1.5 μm. 2. A wafer boat for semiconductor heat treatment, wherein a plurality of slits for loading semiconductor wafers are formed at predetermined intervals on a plurality of support members, wherein at least the support members are provided with a porosity of 0. A wafer boat for semiconductor heat treatment, comprising a glassy carbon material of 2% or less and having a support member having a surface roughness Ra of 0.5 to 1.5 [mu] m. 3. A plurality of support members are arranged in parallel with each other by a pair of upper and lower plate members, and each support member has a plurality of slits for loading a semiconductor wafer at a predetermined interval. Wherein the supporting member, the upper plate and the lower plate are made of a glassy carbon material having a porosity of 0.2% or less, and their surface roughness Ra is 3. The wafer boat for semiconductor heat treatment according to claim 2, wherein the diameter is 0.5 to 1.5 μm. 4. The plurality of support members are arranged so as to project in parallel with each other with respect to an inner surface of the arc-shaped main body,
A horizontal wafer boat in which a plurality of slits for loading semiconductor wafers are formed at predetermined intervals on each support member, wherein the support member and the arc-shaped main body are made of glassy charcoal having a porosity of 0.2% or less. 3. The wafer boat for semiconductor heat treatment according to claim 2, wherein the wafer boat is made of a material and has a surface roughness Ra of 0.5 to 1.5 [mu] m.