JPH0361336B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat treatment system. Conventionally, in a heat treatment system, a semiconductor substrate is inserted into a heating device, a cap is applied to the inlet of the heating device,
A desired gas is introduced and heat treatment is performed for a predetermined period of time. Hereinafter, a conventional heat treatment system will be described in detail with reference to the drawings, using a nitrogen heat treatment system using nitrogen gas as a representative example. Referring to FIG. 1, a semiconductor substrate to be heated 4,
4', the heat treatment jig 1 is inserted into the treatment pipe 6 installed in the heating device 5 using the pull-out rod 2, and the gas supply device 9 is connected by a joint 7 and piping 8. A desired gas is then introduced into the processing tube 6 and heat treatment is performed for a predetermined period of time. Furthermore, cap 3
When the heat treatment jig 1 is inserted into the processing tube 6, the cap is accommodated in the processing tube and serves as a cap. However, when semiconductor substrates processed in the conventional nitrogen heat treatment system described above are inserted into or taken out of the processing tube placed in the heating device, atmospheric oxygen is present near the entrance of the processing tube. Therefore, even though the semiconductor substrate is heated with nitrogen, which is an inert gas, a reaction occurs between the semiconductor substrate and oxygen, and an undesired oxide is formed on the surface of the semiconductor substrate, which is undesirable for semiconductor device manufacturing. There was a flaw that led to the situation. Conventionally used means to compensate for this drawback include a method of rapidly heating or cooling the inside of the heating device to room temperature, that is, rapidly putting the semiconductor substrate into and taking it out of the heating device, and rapidly heating it to room temperature or the desired temperature. A method was used to maintain the temperature. According to this conventional method, since the semiconductor substrate is rapidly cooled or heated to room temperature or the desired heating temperature, the reaction time with oxygen in the atmosphere is shortened, and the formation of undesired oxides can be reduced. It was meant to be. However, when the conventional method is adopted, stress is applied to the semiconductor substrate due to sudden temperature changes, resulting in warpage and cracking of the semiconductor substrate. These warps and cracks are fatal flaws in manufacturing semiconductor devices, and lower yields and quality are unavoidable.In addition, the larger the diameter of the semiconductor substrate, the more the warps and cracks are amplified. However, it was also a hurdle that had to be overcome in the manufacturing of semiconductor devices. SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment system that does not cause warping or cracking of a semiconductor substrate, and does not cause undesired oxides to be formed on the surface of a semiconductor substrate. The present invention is characterized by: a heat treatment jig for arranging a large number of semiconductor substrates facing each other in order in the longitudinal direction; a treatment tube into which the heat treatment jig is inserted from one end; and a treatment tube installed in an internal space; a heating device capable of heating the entire heat treatment jig in the treatment tube to a uniform temperature; a pull-out rod for inserting and extracting the heat treatment jig from the one end of the treatment tube into a predetermined position in the treatment tube; and the treatment tube. In a heat treatment system having a gas supply device that supplies a desired gas into the processing tube from the other end, the processing tube projects horizontally from the heating device, thereby causing a gap between one end of the processing tube and the heating device. The heat treatment jig constitutes a cooling area of the processing tube, and the heat treatment jig is connected to the semiconductor substrate, is arranged at predetermined intervals in the longitudinal direction, and has a cross-sectional area equivalent to 80% or more of the inner diameter cross-sectional area of the processing tube. first and second caps, the first cap being the one end closest to any of the plurality of semiconductor substrates disposed facing each other when the entire heat treatment jig is inserted into the processing tube. The second cap is located between the semiconductor substrates that divide the large number of semiconductor substrates into a plurality of blocks, and the second cap is located between the first cap and the second cap. The distance between the cap and the heat treatment system is less than or equal to the length of the cooling zone of the treatment tube. The present invention will be described in detail below with reference to the drawings, using a nitrogen heat treatment system as a representative example. Referring to FIG. 2, there are 3
Stage caps 3, 3', 3'' are arranged between which semiconductor substrates to be heated 4, 4', 3'' are placed.
The heat treatment jig 1 in this state is put into and taken out of the treatment tube 6 installed in the heating device using the pull-out rod 2. Then, the treatment tube 6 is placed in the heating device. In the longitudinal direction of the heating device, a temperature transition region where the temperature gradually increases is formed at a position facing the center from each end of the heating device, and a temperature transition region where the temperature gradually increases is formed at a position facing the center of the heating device. At this time, if a cooling zone 6' is installed on the extension of the processing tube 6, a state in which the first stage cap 3'' does not cover the end of the cooling zone 6', that is, oxygen in the atmosphere is present. Even in a state equivalent to that of a conventional heat treatment system, the semiconductor substrate 4'' to be heated is still located in the cooling zone 6', where the open end of the treatment tube is separated by at least the second stage cap 3'. Therefore, even though oxygen exists in the atmosphere, no reaction occurs between the semiconductor substrate 4'' and oxygen, and no undesired oxide is formed on the surface of the semiconductor substrate. Note that the length of the cooling zone needs to be set longer than the distance between the caps arranged on the heat treatment jig. When the heat treatment jig is further inserted into the treatment tube, the first stage cap 3'' fits into the treatment tube 6 and functions as a cap, retaining the nitrogen gas introduced into the treatment tube 6. As a result, the influence of oxygen in the atmosphere is completely blocked. From then on, the second stage cap 3' plays the same role as the cap 3'', and when inserted, the third stage cap 3' The cap 3 plays the same role as the cap 3" as described above. On the other hand, when the heat treatment jig 1 is pulled out from the processing tube 6, the same situation as when it is inserted occurs, but the same cap as when it is inserted. 3, 3', 3'' and the cooling zone 6', no undesirable oxide is formed on the semiconductor surface. The size of the cap, that is, the cross-sectional area, depends on the cross-sectional area of the inner diameter of the processing tube, but it has been found that it is effective if it is 80% or more of the cross-sectional area of the inner diameter of the processing tube.
Undesired oxides are not formed on the semiconductor surface. Table 1 shows the effects of the present invention, and shows the thickness of the silicon dioxide film, which is an oxide, measured after introducing nitrogen gas into the processing tube at 1000°C, inserting a silicon substrate, which is a semiconductor substrate, and processing for 10 minutes. The results are shown in which the conventional nitrogen heat treatment system and the nitrogen heat treatment system according to the present invention are compared and contrasted using an ellipsometer. Note that the value measured with the ellipsometer has 10 to 15 (Å) added as a background, and the silicon substrate used has a boron dome of 0.8 to 1.0×10 ¹⁵ (cm ³ ).

[Table] As can be seen from Table 1, the present invention does not cause the formation of undesired oxides. The present invention has been explained above using a nitrogen heat treatment system that uses nitrogen gas as a representative example. However, it is a system that processes semiconductor substrates by heating, in which an undesired oxide film must not be present, that is, argon, helium gas, etc. Heat treatment systems that use inert gases such as, systems that simultaneously process large numbers of relatively thin silicon dioxide films with good uniformity, and semiconductor device manufacturing that may cause quality and yield declines when affected by oxygen. It can be used in a wide variety of systems. Furthermore, although the number of stages of caps on the heat treatment jig 1 is limited to three stages in the explanation, it is possible to arrange more caps by increasing the length of the processing tube 6 and the temperature uniform region of the heating device. If possible, it is possible to create a heat treatment system having three or more stages of caps.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram and a cross-sectional model diagram showing a conventional heat treatment system, and FIG. 2 is a schematic diagram and a cross-sectional model diagram showing an embodiment of the present invention. In the figure, 1 is a heat treatment jig, 2 is a pull-out rod, 3, 3', 3'' is a cap, 4, 4',
4″ is a semiconductor substrate, 5 is a heating device, 6 is a processing tube,
6' is a cooling area, 7 is a joint, 8 is a pipe, and 9 is a gas supply device.

Claims (1)

[Claims] 1. A heat treatment jig for arranging a large number of semiconductor substrates facing each other in order in the longitudinal direction, a processing tube into which the heat treatment jig is inserted from one end, and the processing tube is installed in an internal space, and the a heating device capable of heating the entire heat treatment jig to a uniform temperature; a drawer rod for inserting and removing the heat treatment jig from the one end of the treatment tube into a predetermined position within the treatment tube; and a drawer rod from the other end of the treatment tube. In a heat treatment system having a gas supply device for supplying a desired gas into the processing tube, the processing tube projects horizontally from the heating device, thereby cooling the processing tube between one end of the processing tube and the heating device. The heat treatment jig is connected to the semiconductor substrate, is arranged at a predetermined interval in the longitudinal direction, and has a cross-sectional area equivalent to 80% or more of the inner diameter cross-sectional area of the processing tube. a second cap, and the first cap is located closest to the one end than any of the plurality of semiconductor substrates arranged to face each other when the entire heat treatment jig is inserted into the processing tube. The second cap is located between semiconductor substrates that divide the large number of semiconductor substrates into a plurality of blocks, and the second cap is located between the first cap and the second cap. A heat treatment system characterized in that the distance is less than or equal to the length of the cooling zone of the treatment tube.