JP2002076100A - Silicon boat and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon boat and a method for manufacturing it to reduce particles created during thermal processing. SOLUTION: The method for manufacturing the silicon boat for supporting a semiconductor wafer W during thermal process comprises: a process of forming a silicon material into a boat by mechanical processing; and a process of removing or thinning a damaged layer D on the surface of the silicon material created by the mechanical processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon boat used for supporting a silicon wafer or the like when heat treatment such as hydrogen annealing is performed on the silicon wafer or the like.

[0002]

2. Description of the Related Art In a heat treatment of a silicon wafer or the like performed in a process of a semiconductor device or the like (for example, a heat treatment in a reducing atmosphere such as a hydrogen annealing treatment), a silicon boat (hereinafter, referred to as a heat treatment) from the viewpoint of strength and contamination. A silicon boat is used as a jig for supporting a wafer. To make this silicon boat,
Since the silicon material is a hard material, shaping is performed by rotating a blade having diamond abrasive grains applied to the silicon material.

[0003]

However, the above-described method for manufacturing a silicon boat has the following problems. That is, when the silicon boat is cut, the surface of the silicon material is easily damaged, and various inconveniences occur when used for heat treatment. In particular, the damage caused during cutting may be etched in a reducing atmosphere such as hydrogen annealing to generate particles, and the number of particles due to such damage increases, which may cause defects on the wafer surface during heat treatment. There was a problem that particles were attached.

[0004] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a method of manufacturing a silicon boat in which particles are less likely to be generated during heat treatment and a silicon boat.

[0005]

The present invention has the following features to attain the object mentioned above. That is, the method for manufacturing a silicon boat according to the present invention is a method for manufacturing a silicon boat for supporting a semiconductor wafer during heat treatment of a semiconductor wafer, the method comprising: forming a silicon material into a boat shape by machining; Removing or thinning a damaged layer on the surface of the silicon material generated by processing.

In this method of manufacturing a silicon boat, a damaged layer on the surface of a silicon material generated by machining is removed or thinned, so that there is no damaged layer on the surface or the number of damaged layers on the surface is reduced, resulting in damage. The increase in particles can be suppressed, and the dimensional accuracy does not deteriorate because only the damaged layer is removed.

In the method for manufacturing a silicon boat according to the present invention, in the step of removing or thinning the damaged layer,
It is preferable to perform the determination based on the depth of the damage layer generated by the machining that has been checked in advance. That is, by determining the depth to be removed based on the depth of the damaged layer generated by the previously checked machining, only the damaged layer can be accurately removed, and the dimensional accuracy can be maintained satisfactorily by the minimum necessary removal amount. be able to.

In the method of manufacturing a silicon boat according to the present invention, in the step of removing or thinning the damaged layer,
Preferably, it is removed from the surface of the silicon material by a depth of 30 μm. In other words, in a silicon board cut by a diamond abrasive blade, damage is usually generated at a depth of 30 μm or less from the surface, so by removing only 30 μm from the surface,
The damaged layer can be reliably removed.

In the method for manufacturing a silicon boat according to the present invention, the step of removing or thinning the damaged layer may include:
It is preferably performed by chemical etching or chemical mechanical polishing. In other words, when the damaged layer is removed by machining, even if the abrasive grain size is set to a small value, a considerable amount of damage remains, whereas if the damaged layer is removed by chemical etching or chemical mechanical polishing, particle Almost no damage is caused at the time of removal.

In the method for manufacturing a silicon boat according to the present invention, the step of forming the boat into the shape of the boat and the step of removing or thinning the damaged layer may be performed by rotating a blade having diamond abrasive grains on the silicon material. The step of removing or thinning the damaged layer is performed by abutting, polishing is performed with a diamond abrasive grain smaller than the blade used for the mechanical processing, and the diamond abrasive grains of this blade are stepped. It is also possible to adopt a technique of performing the process while reducing the size. In other words, in this method of manufacturing a silicon boat, the polishing is performed while the diamond abrasive grains are reduced in a stepwise manner. Can be removed or thinned.

Further, a silicon boat according to the present invention is a silicon boat for supporting a semiconductor wafer during heat treatment of a semiconductor wafer, and is manufactured by the method for manufacturing a silicon boat according to the present invention. In other words, in this silicon boat, there is almost no generation of particles due to damage during cutting during the heat treatment. Therefore, the use of this boat can prevent the occurrence of defects due to particle adhesion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a silicon boat and a silicon boat according to the present invention will now be described with reference to FIG.
This will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a silicon boat, 2 denotes a top plate member, 3 denotes a bottom plate member, 4
Indicates a support member.

FIG. 1 shows a silicon boat 1 of the present invention, and FIG. 2 shows a batch type vertical heat treatment furnace using the silicon boat 1. Silicon boat 1
As shown in FIG. 1 and FIG. 2, a plurality of silicon wafers (semiconductor wafers) W can be mounted thereon, and each member formed of a silicon material (polysilicon) is assembled.

The silicon boat 1 has a top plate member 2 and a bottom plate member 3 provided to face each other up and down, and a plurality of the silicon boats 1 are vertically installed in parallel with each other between the top plate member 2 and the bottom plate member 3. And a rod-shaped support member 4. Each support member 4 has a support groove 4a into which a peripheral portion of the silicon wafer W can be inserted and which supports the silicon wafer W in a horizontal state.
Are formed at intervals in the vertical direction.

As shown in FIG. 2, for example, a heat treatment furnace using the silicon boat 1 has a cylindrical quartz reaction tube 5 into which the silicon boat 1 can be inserted from below, and covers the periphery of the quartz reaction tube 5. , A heater 6 for heating the silicon wafer W in the quartz reaction tube 5, a gas supply source 7 connected to the inside of the quartz reaction tube 5 for supplying hydrogen gas and the like, and supporting and moving the silicon boat 1 up and down. And an elevator mechanism 8 which is inserted into the quartz reaction tube 5 and pulled out below the quartz reaction tube 5.

That is, when performing a hydrogen annealing treatment of, for example, a silicon wafer W by this heat treatment furnace, first, the silicon wafer W is placed on the silicon boat 1,
This is raised by the elevator mechanism 8 and the quartz reaction tube 5
Insert and place inside. Then, the inside of the quartz reaction tube 5 is heated to a predetermined temperature by the heater 6, and a hydrogen gas is supplied from the gas supply source 7 into the quartz reaction tube 5 to form a hydrogen atmosphere (reducing atmosphere). This is performed by heat-treating W.

In order to manufacture the silicon boat 1, each of the above-mentioned members constituting the silicon boat 1 is formed by cutting (machining) a silicon material with a diamond abrasive blade. Next, the damaged layer on the surface of each of the above-mentioned members generated during cutting is removed before or after assembling the members using hydrofluoric nitric acid (for example, HF / HNO ₃ = 1/1).
0) or alkaline etchant (for example, KOH etc.)
Removed or thinned by chemical etching. At this time, a similar cutting process is performed on a member made of another silicon material in advance, the depth of the damaged layer generated at this time is checked, and this depth is set as the surface removal amount.

As described above, in this embodiment, since the damaged layer on the surface of the silicon material generated by the cutting process is removed by chemical etching, there is no damaged layer on the surface, and it is possible to suppress an increase in particles caused by the damage. In addition, the dimensional accuracy is not degraded because only the damaged layer is removed. In addition, by determining the depth to be removed based on the depth of the damaged layer generated by the cutting process checked in advance, it is possible to accurately remove only the damaged layer,
The dimensional accuracy can be maintained satisfactorily by the minimum necessary removal amount. Note that a depth of 30 μm from the surface may be set as the removal amount of the surface. That is, as shown in FIG. 3, the damage layer D generated by the cutting process using the diamond abrasive blade is usually within 30 μm from the surface, so that the damage layer D can be reliably removed.

[0019]

EXAMPLE Table 1 shows the result of examining the level of particles adhering to the surface of a silicon wafer W subjected to hydrogen annealing by the heat treatment furnace using the silicon boat 1 manufactured by the manufacturing method of this embodiment. For comparison, Table 2 shows the result of examining the level of particles attached to the silicon wafer surface when hydrogen annealing was similarly performed using a conventional silicon boat. In addition, the particle level is set to 0.1 when the particle size exceeds 0.2 μm.
Tables 1 and 2 show the number of adhering particles (per wafer) detected at a particle size exceeding 3 μm.

[0020]

[Table 1]

[Table 2]

As can be seen from Tables 1 and 2, when the silicon boat 1 according to the present embodiment is employed, any of those having a particle size of more than 0.2 μm and those having a particle size of more than 0.3 μm as compared with the conventional silicon boat. In the case of the above, the average number of adhered particles is significantly reduced. In addition, as a result of examining the average use time until maintenance of the silicon boat 1 according to the present embodiment, it was found that the use time was greatly extended as compared with the conventional example.

The technical scope of the present invention is not limited to the above embodiment, and various changes can be made without departing from the spirit of the present invention. In the above embodiment, the damaged layer is removed by chemical etching, but may be removed by chemical mechanical polishing. Also in this case, as in the case of chemical etching, mechanical damage is not caused at the time of removal, and high dimensional accuracy can be obtained.

In the above embodiment, the damaged layer is removed by chemical etching. However, the surface is polished by a diamond abrasive blade smaller than the blade used for the cutting for forming the boat, and the damaged layer is removed. May be removed or thinned. In this case,
By gradually reducing the size of the diamond abrasive grains of this blade (by replacing it with a finer one), it is possible to remove or reduce the damage layer to almost negligible extent only by replacing the blade. Thus, it becomes unnecessary to remove the damaged layer by the chemical etching, or it can be reduced to a small amount (less than 3 μm).

[0024]

According to the present invention, the following effects can be obtained.
According to the method for manufacturing a silicon boat of the present invention, since the damaged layer on the surface of the silicon material generated by machining is removed or thinned, there is no damaged layer on the surface or the number of damaged layers on the surface is reduced, resulting in damage. In addition, it is possible to obtain a boat capable of performing a good heat treatment without deteriorating dimensional accuracy because only the damaged layer is removed.

According to the silicon boat of the present invention,
Since the silicon boat is manufactured by the method of manufacturing a silicon boat according to the present invention, there is almost no generation of particles due to damage during processing during the heat treatment, and it is possible to prevent the occurrence of defects due to particle adhesion.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing a silicon boat in one embodiment of a method for manufacturing a silicon boat and a silicon boat according to the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a heat treatment furnace in one embodiment of the method for manufacturing a silicon boat and the silicon boat according to the present invention.

FIG. 3 is an explanatory view schematically showing a cross section near a surface after machining in a silicon boat manufacturing method and a silicon boat according to an embodiment of the present invention.

[Explanation of symbols]

 1 Silicon boat D Damage layer W Silicon wafer (semiconductor wafer)

Continued on the front page (72) Inventor Yoshinobu Nakata 1-5-1, Otemachi, Chiyoda-ku, Tokyo Mitsubishi Materials Silicon Co., Ltd. F-term (reference) 5F031 CA02 HA62 HA63 MA30 PA26

Claims (6)

[Claims] 1. A method of manufacturing a silicon boat for supporting a semiconductor wafer during heat treatment of a semiconductor wafer, comprising: forming a silicon material into a boat shape by machining; and forming the silicon material by the machining. Removing or thinning the damaged layer on the surface of the silicon boat. 2. The method for manufacturing a silicon boat according to claim 1, wherein the step of removing or thinning the damaged layer is performed based on a depth of the damaged layer generated by the mechanical processing which is checked in advance. Silicon boat manufacturing method. 3. The method for manufacturing a silicon boat according to claim 1, wherein the step of removing or thinning the damaged layer comprises removing the silicon layer by a depth of 30 μm from the surface of the silicon material. Production method. 4. The method for manufacturing a silicon boat according to claim 1, wherein the step of removing or thinning the damaged layer is performed by chemical etching or chemical mechanical polishing. Silicon boat manufacturing method. 5. The method for manufacturing a silicon boat according to claim 1, wherein the step of forming the boat into a shape of the boat and the step of removing or thinning the damaged layer are performed by using a hardened diamond abrasive. The step of removing or thinning the damaged layer is performed by polishing with a diamond abrasive blade smaller than the blade used for the machining, and the blade is removed by rotating the blade. A method for producing a silicon boat, wherein the method is performed while gradually reducing the diamond abrasive grains. 6. A silicon boat for supporting a semiconductor wafer during heat treatment of the semiconductor wafer, the silicon boat being manufactured by the method for manufacturing a silicon boat according to claim 1. boat.