JPH1167889A - Storage box for semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a storage box by which the surface of a semiconductor substrate is maintained clean, in a semiconductor manufacturing process and a material treatment process. SOLUTION: A lid body 2 which formed a set together with a container body 1 in a storage box is formed as an integrated structure, which is provided with a filter for organic gas removal and a filter 3 for particle removal. The filter 3 for organic-gas removal 3 is used to capture and remove an organic gas generated inside the container body 1. The filter 3 for particle removal is used to capture and remove particles which creep into the container body 1. In addition, the container body 1 is constituted of a metal-free synthetic resin, which does not discharge an organic substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate storage box used for storage and movement during a semiconductor manufacturing process.

[0002]

2. Description of the Related Art With the miniaturization of VLSI, the demand for cleaning the surface of a semiconductor substrate has become more and more intense. In particular, metal impurities are fatal when attached to the surface of a semiconductor substrate, and significantly deteriorate the electrical characteristics of a semiconductor device. Generally, the surface metal pushing concentration of the semiconductor substrate is 1
It is said that it is necessary to set the level to × 10 ⁹ atoms / cm ² or less. Therefore, at present, the storage boxes for semiconductor substrates use metal-free materials.

However, recently, the emission of organic gas and the adsorption to the surface of a semiconductor substrate, which are considered to be caused by a clean room atmosphere or a plastic storage box, have become problems. It has also been found that when these organic gases are adsorbed on the semiconductor substrate, the electrical characteristics of the semiconductor device are degraded. For example, when a semiconductor substrate is stored in a storage box or in a clean room atmosphere before and after gate oxidation, deterioration of the gate oxide film breakdown voltage is caused depending on the storage time. Now that the gate oxide film is becoming thinner, it is necessary to further reduce metal impurities and organic impurities which have not been regarded as a problem at the same time.

[0004] Therefore, it has become particularly important to avoid contamination of organic substances from the atmosphere of a clean room, storage box materials and the like as much as possible.

[0005] There are the following four types of conventional semiconductor substrate storage methods. The first method is a method of storing in a PP (polypropylene) storage box. In this method, organic contamination is avoided by keeping the storage time below a certain fixed time.

As a second method, a semiconductor substrate is stored in a storage box made of PC (polycarbonate) or PP, and then the clean room air in the storage box is replaced with N ₂ and stored. Even when the semiconductor device is introduced into a semiconductor manufacturing apparatus, it is introduced by a local clean system without directly touching the atmosphere of the clean room.

[0007] As a third method, Japanese Patent Laid-Open Publication No.
As disclosed in No. 51, the material of the storage box is not limited. The gas is forcibly circulated. This has a structure in which the atmosphere other than the outside air inlet is not directly in contact with the clean room atmosphere.

[0008] As a fourth method, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 87, means for increasing the internal pressure of a storage box made of a synthetic resin such as PP or PFA (perfluoroalkoxy) above the external pressure, and a water-soluble coating formed inside the storage box are used. And a means for cooling the storage box. The presence of the water-soluble coating avoids the adsorption of the organic gas released from the storage box to the semiconductor substrate.

[0009]

However, in the first method, the allowable time until the next process is determined. However, depending on the cleanliness of the atmosphere in the clean room and the type of the storage box, the amount adsorbed on the semiconductor substrate may vary. Is not constant,
Further, in the process of forming a gate oxide film having a thickness of 10 nm or less, the allowable time may be 10 minutes or less in some cases, and it is difficult to actually manage the gate oxide film. There was a problem that growth was promoted.

Further, in the second method, since the semiconductor substrate is stored by substituting N ₂ and the system is a closed system, it is possible to control particles, natural oxide films, and the like. However, as the storage time becomes longer, it becomes clear that the organic substances from the adhesive and other materials used to seal the box are gasified and released into the storage box, and are adsorbed on the semiconductor substrate. Have been. Furthermore, it is necessary to provide an introduction system for a semiconductor substrate with a local clean system in all semiconductor manufacturing apparatuses, and there is a problem in that the cost is enormous.

In the third method, since a difference is generated between the internal pressure and the external pressure, adhesion of particles and the like are prevented. Further, entry of organic gas from the clean room atmosphere can be avoided. However, several types of organic solvents are used to form a water-soluble film on the surface of a semiconductor substrate, but lower alcohols and the like evaporate immediately after being adsorbed on the semiconductor substrate, affecting the device characteristics. Although it is known that it is difficult to give, ketones and carboxylic acids having oxygen are easily adsorbed on the surface of the semiconductor substrate even when the vapor pressure is high. And it is becoming clear that there is an influence on the device because it cannot be completely removed by washing with water or the like.
In order to control the organic gas released from the storage box,
Forming such a coating and exposing the semiconductor substrate to an organic solvent is very problematic.

In the fourth method, the atmosphere gas is cleaned by an activated carbon filter and a membrane filter. Since all are closed systems, generation of particles and organic gas and chemical contamination can be prevented. However, although useful for long-term storage, it is inconvenient to store and move the waiting time between processes, making it difficult to move to the front of the processing equipment. Since the transfer is performed after the transfer, there is a concern that the particles and the organic gas are contaminated similarly to the first method.

In the first and second methods, the storage box can be moved between devices as a storage box, but there is a concern that the storage box body may be contaminated with organic gas or the like. In particular, in the second method, it is necessary to ground the introduction system of the semiconductor substrate on the semiconductor manufacturing apparatus side, which requires enormous cost and installation area.

Further, in the third and fourth methods, since the devices are devices, it is extremely difficult to move them, and the devices must be moved using the first or second method. In particular, the third method has a problem of contamination by a solvent used for forming a film.

That is, in the above-mentioned four types of conventional techniques, it is not easy to store and move from the previous process to the next process while keeping the semiconductor substrate clean.

An object of the present invention is to prevent the organic gas released from a clean room environment and a storage box from adsorbing on the surface of a semiconductor substrate, and to maintain the cleanliness of the semiconductor substrate and to quickly move to the next step. To provide a storage box.

[0017]

In order to achieve the above object, a storage box for a semiconductor substrate according to the present invention is a storage box for a semiconductor substrate comprising a combination of a container body and a lid. The semiconductor substrate is housed therein, and the lid covers the container body, and has an integral structure equipped with a filter for removing organic gas and a filter for removing particles.

The container body is made of a metal-free synthetic resin which hardly releases an organic gas.

The metal-free synthetic resin which hardly releases the organic gas is PC (polycarbonate), PEE
K (peak), PTEF (pertetrafluoroethylene)
Or PFA (perfluoroalkoxy) or a mixture thereof.

The filter for removing organic gas and the filter for removing particles of the lid are packaged with a material which does not easily release organic gas.

The container body and the lid have a ventilation structure, and have a self-cleaning function for avoiding adsorption of an organic gas to the surface of the semiconductor substrate by utilizing the circulation of air in a crane room atmosphere.

Further, the container body and the lid have air permeability by a mesh structure.

The container body has a mesh structure on the bottom side.

The container body is made of a metal-free synthetic resin that hardly releases organic substances, and the lid for covering the container body is equipped with a filter for removing organic gas and a filter for removing particles. With this configuration,
The generation of organic gas in the container body is suppressed as much as possible, and the organic gas generated in the container body is captured and removed by an organic gas removing filter.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a storage box for semiconductor substrates according to one embodiment of the present invention.

FIG. 1 shows a semiconductor substrate storage box according to one embodiment of the present invention, which has a self-cleaning function for avoiding adsorption of organic gas to the surface of a semiconductor substrate by utilizing circulation of air in a clean room atmosphere. It is.

More specifically, the semiconductor substrate storage box according to the embodiment of the present invention comprises a container body 1 and a lid 2.
It consists of a combination with

The container body 1 has a structure having a space for accommodating a semiconductor substrate. The container body 1 is made of a metal-free synthetic resin, such as P
C (polycarbonate), PEEK (peak), PTE
It is composed of either F (pertetrachloroethylene) or PFA (perfluoroalkoxy), or a mixture thereof.

The lid 2 hermetically covers the container body 1 and has an integrated structure equipped with a filter for removing organic gas and a filter 3 for removing particles. The organic gas removing filter 3 captures and removes the organic gas generated in the container body 1, and the particle removing filter 3 captures and removes the particles entering the container body 1. It has become.

The filter for removing organic gas and the filter 3 for removing particles of the lid 2 are made of a material which hardly emits an organic gas, especially PFA (perfluoroalkoxy).
Or it is packaged with PTEF (pertetrachloroethylene) or the like.

Further, the container body 1 and the lid 2 have a self-cleaning function of forming a ventilation structure, utilizing the circulation of air in a clean room atmosphere, and avoiding adsorption of organic gas to the surface of the semiconductor substrate. Specifically, the lid 2
The mesh structure 4 is provided on the surface facing the organic gas removal filter and the particle removal filter 3 to ensure air permeability. The mesh structure 4 is 0.1 to 1 m
The structure is such that a mesh of mφ is provided. In addition, the container main body 1 secures air permeability through the mesh structure 5 on the bottom side. The mesh structure 5 has a structure in which an exhaust port having a diameter of about 1 mm is provided at a corner on the bottom side of the container body 1.

In using the storage box according to the embodiment of the present invention, first, a semiconductor substrate is stored in the container body 1, the container body 1 is covered with the lid 2, and this is set in a clean room atmosphere. I do. Air in a clean room atmosphere passes through the particle removing filter 3 through the mesh structure 4 of the lid 2. The air in the clean room atmosphere is purified when passing through the particle removal filter 3, and the purified air is blown into the container body 1.

Here, even if the container body 1 is made of a material that releases little organic gas, a small amount of organic gas is released from inside the container body 1. These organic gases are trapped and adsorbed by the organic gas removing filter 3 of the lid 2, and from the mesh structure (vent) 5 on the bottom side of the container main body 1 by the circulation of the air flow in a clean room atmosphere. 1 in some cases.

If there is no air flow in the container body 1, the air
The generated gas is likely to be adsorbed on the surface of the semiconductor substrate due to the solid equilibrium. However, when air is circulated, the organic gas is discarded to the outside of the container body 1 by the air flow rather than adsorbed on the surface of the semiconductor substrate, The semiconductor substrate in the container body 1 is kept in a clean state.

The organic gas generated in the container body 1 is captured and adsorbed by the organic gas removing filter 3 of the lid 2, so that the semiconductor substrate in the container body 1 is kept in a clean state. You.

Also, when moving from the previous step to the next step, the movement can be easily performed, and there is no need to modify the system for introducing the semiconductor substrate into the apparatus.

(Example) Next, an example of the embodiment of the present invention will be described as an example. The wafer after the formation of the gate oxide film of 10 nm or less is stored in the storage box shown in FIG. At the same time, it is stored in a conventional PP (polypropylene) subcase as a comparative experiment. This has a higher degree of sealing than an ordinary box. afterwards,
According to the long-term reliability evaluation of the gate oxide film, when the semiconductor substrate is stored in the storage box according to the embodiment of the present invention, the amount of the organic substance in the container body 1 is reduced even if it exceeds 72 hours. The breakdown voltage of the film does not reach an amount that causes an abnormality, and the breakdown voltage of the gate oxide film is good. However,
When stored in the subcase, the total amount of organic substances on the surface of the semiconductor substrate exceeded 0.2 ng / cm2, and the breakdown voltage of the gate oxide film was deteriorated.

FIG. 2 shows the results of long-term reliability evaluation (TDDB characteristic evaluation) of the gate oxide film when stored in the subcase and the storage box of the present invention for 72 hours. In the storage box of the present invention, the TDDB characteristic does not deteriorate, but in the subcase storage, the deterioration is observed.

FIG. 3 shows that the storage box of the present invention has a thickness of 10 nm.
The organic matter on the surface of the semiconductor substrate (wafer) when the wafer on which the following gate oxide film was grown was stored for 18 hours,
The results of measurement with a thermal desorption gas chromatograph mass spectrometer are as follows. FIG. 4 shows that a semiconductor substrate (wafer) on which a gate oxide film having a thickness of 10 nm or less was grown in a conventional box was stored for 18 hours. The results are as follows. As is clear from the figure, when the semiconductor substrate is stored in the storage box according to the embodiment of the present invention, the organic matter is approximately 0.1 ng / cm.
Less than ² levels. On the other hand, in a normal box, it is at least 0.3 ng / cm ² level.

FIG. 5 shows the amount of organic substances on the surface of the semiconductor substrate when the wafer was stored for 4.5 hours, 22 hours, and 53 hours in a normal box made of PP (having a sealing property worse than that of the subcase). Is shown. As is clear from FIG. 5, the amount of organic matter increases with time. 4.
The amount of organic substances on the surface of the semiconductor substrate in 5 hours was 0.2 ng /
whereas a cm ² or less level, in storage at 53 hours has increased to approximately 5 ng / cm ^2. When stored in such a conventional box, no deterioration of the gate oxide film is observed in 4.5 hours, but when stored for 22 hours or more, the breakdown voltage of the gate oxide film is deteriorated.

As a comparative example, when the semiconductor substrate after gate oxidation is stored in the N ₂ substitution box, as shown in FIG. 6, the amount of organic substances on the surface of the semiconductor substrate is as follows. When stored for about one week, the N ₂ replacement box is a closed system, so there is no increase in particles,
Organic matter increases. As for the kind of the organic substance, an adhesive used for increasing the degree of sealing and other organic substances originating from a box occupy a large number. Since the main component of the box is PC (polycarbonate), contamination from the main component is slight. Organic substances that degrade the withstand voltage of the gate oxide film mainly include phthalic acid esters having benzene rings and oxygen, antioxidants, and the like, and saturated hydrocarbons and ethers are not significantly affected. Therefore, not only the total organic substances on the semiconductor substrate, but also the adsorption of the organic substances having a high influence may degrade the breakdown voltage of the gate oxide film even in a small amount.

Table 1 shows the amount of organic substances (semi-quantitative value) on the surface of the semiconductor substrate when the semiconductor substrate before and after the gate oxidation is stored in the conventional N ₂ substitution box and subcase.

[0044]

TABLE 1 N ₂ organic matter on the surface of the semiconductor substrate when stored the semiconductor substrate, across the gate oxide to substituted box and subcase (semi-quantitative value) semi-quantitative value ng (C ₁₆ conversion) (1 week)

When the gate oxide film becomes thinner, the influence of organic matter is further exerted. However, if stored in the storage box of the present invention, such deterioration in pressure resistance can be avoided even for 72 hours or more.

The above-described semiconductor substrate storage box according to the embodiment of the present invention shown in FIG. 1 is a self-cleaning device that utilizes the circulation of air in a clean room atmosphere to avoid organic gas adsorption on the semiconductor substrate surface. Although it has a function, the present invention is not limited to a device having a self-cleaning function.

Although the present invention has been described with reference to a storage box for semiconductor substrates, the configuration of the storage box according to the present invention can be used to store semiconductor substrates when moving from a previous step to the next step or in a storage box. The present invention can be similarly applied to a carrier or a carrier box used when performing the method, and the present invention is not limited to a storage box for semiconductor substrates.

[0048]

As described above, according to the present invention, the amount of the organic gas component adsorbed on the semiconductor substrate during the waiting time from the previous process to the next process of the semiconductor manufacturing process can be significantly reduced. The deterioration of the characteristics of the semiconductor device can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a storage box according to an embodiment of the present invention.

FIG. 2 is a diagram showing TDDB characteristics of a gate oxide film in subcase storage and storage box storage of the present invention.

FIG. 3 is a view showing the amount of organic substances on a wafer surface when the wafer is stored in a storage box of the present invention after a gate oxide film is formed.

FIG. 4 is a view showing the amount of organic substances on a wafer surface when the wafer is stored after forming a gate oxide film in a subcase.

FIG. 5 is a view showing the amount of organic substances on the wafer surface when the wafer is stored in a carrier box after forming a gate oxide film.

FIG. 6 is a diagram showing the amount of organic substances on a wafer surface when wafers before and after gate oxidation are stored in an N ₂ substitution box and a subcase.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Container main body 2 Lid 3 Organic gas removal filter and particle removal filter 4 Mesh structure 5 Mesh structure

Claims (7)

[Claims] 1. A storage box for a semiconductor substrate, comprising a combination of a container body and a lid, wherein the container body stores the semiconductor substrate, and the lid covers the container body. A semiconductor substrate storage box having an integral structure equipped with a filter for removing organic gas and a filter for removing particles. 2. The storage box for semiconductor substrates according to claim 1, wherein said container body is made of a metal-free synthetic resin that hardly releases an organic gas. 3. The metal-free synthetic resin which hardly releases an organic gas includes PC (polycarbonate) and PEEK.
(PE), one of PTEF (pertetrafluoroethylene) and PFA (perfluoroalkoxy), or a mixture thereof.
A storage box for a semiconductor substrate according to claim 1. 4. The semiconductor substrate according to claim 1, wherein the filter for removing organic gas and the filter for removing particles of the lid are wrapped with a material that hardly emits organic gas. Storage box. 5. The container body and the lid have a self-cleaning function which has a ventilation structure, utilizes circulation of air in a crane room atmosphere, and avoids adsorption of organic gas to the surface of the semiconductor substrate. The storage box for a semiconductor substrate according to claim 1, 2, or 3, wherein: 6. The storage box for a semiconductor substrate according to claim 4, wherein the container body and the lid have air permeability by a mesh structure. 7. The semiconductor substrate storage box according to claim 4, wherein the container body has a mesh structure on a bottom side.