JP2013182916A - Thermal diffusion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal diffusion device capable of forming a uniform diffusion layer by supplying a diffusion source of uniform concentration to a body to be diffused.SOLUTION: A thermal diffusion device includes a reaction pipe 10 in which a reaction chamber 11 for subjecting a body 2 to be diffused to diffusion processing is formed, a heater 4 which heats the body 2 to be diffused from a periphery of the reaction pipe 10, and a gas introduction pipe 7 which introduces into the reaction pipe 10 a gas including a diffusion source for forming a diffusion layer on the body 2 to be heated having been heated by the heater 4. The interior of the reaction pipe 10 is partitioned into the reaction chamber 11 and a laminar space 13 in which the gas from the gas introduction pipe 7 flows at a periphery of the reaction chamber 11, and a plurality of inflow holes 14 for allowing the gas having passed through the laminar space 13 to flow in the reaction chamber 11 at a periphery of the body 2 to be diffused are formed in a partition wall 12 partitioning off the reaction chamber 11 and the laminar space 13.

Description

  The present invention relates to a thermal diffusion device, and more particularly to a thermal diffusion device used in a diffusion process for forming a diffusion layer on a semiconductor wafer.

  Conventionally, in a diffusion process, a thermal diffusion furnace has been widely used because of its simple structure and the ability to process many objects to be diffused at one time. The material to be diffused is disposed inside the reaction tube to which the gas introduction tube is connected. The diffused material is held on the boat in a state where one surface thereof is parallel or perpendicular to the longitudinal direction of the reaction tube. Usually, a diffusion source that is a liquid or a gas and an inert gas that is a carrier gas for sufficiently spreading the diffusion source to the inside of the reaction tube are introduced into the reaction tube from the gas introduction tube.

  In thermal diffusion, the dopant distribution in the surface of the diffused material may become non-uniform by processing many diffused materials at a time. The causes include temperature distribution in the diffused material, concentration distribution of the diffusion source, re-diffusion between adjacent diffused materials in the diffusion process, and the like. Among these factors, the influence of the temperature distribution of the diffused material and the concentration distribution of the diffusion source is considered to be large.

  The temperature distribution of the diffused material is mainly caused by uneven temperature inside the reaction tube. The reason why the temperature inside the reaction tube is uneven is that the arrangement of the heater in the heat diffusion device, the heat transfer when the diffusion object is carried into the reaction tube, and the diffusion object due to the gas introduced into the reaction tube Cooling.

  The concentration distribution of the diffusion source is mainly caused by the non-uniform gas flow inside the reaction tube. By adopting a configuration in which the gas flow in the surface of the object to be diffused becomes uniform inside the reaction tube, the diffusion source can be distributed at an even concentration. For example, if a shielding plate is installed at a position that blocks the gas flow upstream of the reaction tube so that the gas introduced into the reaction tube does not directly contact the diffused material, the gas containing the diffusion source directly contacts the diffused material. Compared with the case where it does, the density | concentration of a diffusion source is equalized about the longitudinal direction inside a reaction tube.

  As a means for suppressing the deterioration of the dopant distribution, for example, a technique of rotating the diffused object inside the reaction tube is known. A rotation mechanism is provided inside the reaction tube. As a basic configuration, the reaction tube is arranged in a vertical direction in which the longitudinal direction is the vertical direction. The object to be diffused is placed on a susceptor having a countersink for preventing a fall in the diffusion process. The susceptor is inserted into a rotatable sample holder.

  By placing the reaction tube vertically, the diffused material is carried in and out from the lower side of the reaction tube. Usually, an excessive diffusion source in the diffusion process is deposited inside the reaction tube. In particular, a thermal diffusion device used as a production facility requires periodic cleaning of the reaction tube. In order to be able to take out the reaction tube from the heat diffusing device, the heat diffusing device needs to be at least twice as high as the reaction tube. For this reason, when rotating a diffused object, while distribution of the dopant in the surface of a diffused object becomes favorable, the enlargement of a thermal-diffusion apparatus becomes a problem. In addition, since the diffused material is disposed horizontally, dust generated inside the reaction tube may fall on the diffused material. The adhesion of dust can cause pattern disconnection and poor characteristics in semiconductor microfabrication.

  As a technique for obtaining a uniform diffusion layer without adopting the rotating mechanism of the diffused material, for example, a technique has been proposed in which gas introduction pipes are arranged vertically and horizontally with respect to the cylindrical axis of the reaction pipe (for example, patents) Reference 1). The gas containing the diffusion source is released from the top, bottom, left, and right inside the reaction tube to the object to be diffused.

JP 2009-194001 A

  In the case of the technique disclosed in Patent Document 1, the gas including the diffusion source passes through the gas introduction tube having a very small volume with respect to the reaction tube, so that the flow velocity is increased and the gas is introduced into the reaction tube. If the gas reaches the diffusion object without being sufficiently heated due to an increase in the gas flow rate, the diffusion object is cooled, and it becomes difficult to obtain a uniform diffusion layer. In addition, when a gas introduction pipe with a complicated structure is arranged inside a reaction pipe generally made of quartz, it is very difficult to remove and adjust the position of the reaction pipe and gas introduction pipe for cleaning, especially in mass production facilities. It becomes complicated.

  The present invention has been made in view of the above, and provides a thermal diffusion device capable of forming a uniform diffusion layer by supplying a diffusion source with a uniform concentration to an object to be diffused. Objective.

  In order to solve the above-described problems and achieve the object, the present invention provides a reaction tube in which a reaction chamber for performing diffusion treatment on a diffusion object is formed, and the diffusion object from the periphery of the reaction tube. And a gas introduction pipe for introducing a gas including a diffusion source for forming a diffusion layer in the diffusion object heated by the heater into the reaction tube, and the reaction tube Is partitioned into the reaction chamber and a laminar space in which the gas from the gas introduction pipe flows around the reaction chamber, and the partition wall that divides the reaction chamber and the laminar space includes the lamellar space. A plurality of inlets are formed for allowing the gas that has passed through the space to flow into the reaction chamber around the diffused material.

  According to the present invention, the thermal diffusion device causes the gas containing the diffusion source to flow into the layered space around the reaction chamber, and flows into the reaction chamber from the plurality of inlets around the diffusion target. The thermal diffusion device can disperse the diffusion source at a uniform concentration by introducing diffusion sources from multiple directions to the object to be diffused, compared to the case where the diffusion source is introduced from one direction into the reaction tube. Can do. Thereby, the thermal diffusion apparatus can supply a diffusion source with a uniform concentration to the object to be diffused, and form a uniform diffusion layer.

FIG. 1 is a diagram illustrating a schematic configuration of the thermal diffusion device according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of the thermal diffusion device according to the second embodiment of the present invention.

  Embodiments of a thermal diffusion device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a schematic configuration of the thermal diffusion device according to the first embodiment of the present invention. The thermal diffusion device 1 includes a reaction tube 10 and a plurality of heaters 4 arranged around the reaction tube 10. In the reaction tube 10, a reaction chamber 11 for performing a diffusion treatment on the diffusion object 2 is formed inside. The heater 4 heats the diffused material 2 from the periphery of the reaction tube 10. The diffused object 2 is, for example, a semiconductor wafer. The diffusion object 2 is stored in the reaction chamber 11 while being held on the boat 3.

  The reaction tube 10 has a gas introduction tube 7 connected to one end (first end) in the longitudinal direction. The gas introduction pipe 7 introduces into the reaction tube 10 a gas obtained by mixing a diffusion source for forming a diffusion layer on the diffusion object 2 heated by the heater 4 and an inert gas. The inert gas is a carrier gas for sufficiently spreading the diffusion source, which is a gas or a liquid, into the reaction tube 10.

  In the reaction tube 10, an end portion (second end portion) opposite to the first end portion in the longitudinal direction is an opening for loading and unloading the diffused material 2 into and from the reaction chamber 11. The door 5 is responsible for opening and closing the opening. The inside of the reaction tube 10 is sealed by closing the door 5. An exhaust mechanism 6 for reducing the pressure inside the reaction tube 10 is provided in the vicinity of the opening in the reaction tube 10.

  The inside of the reaction tube 10 has a double structure of a reaction chamber 11 and an outer layered space 13. The partition wall 12 partitions the inside of the reaction tube 10 into a reaction chamber 11 and a layered space 13. The layered space 13 surrounds the reaction chamber 11. The gas introduced by the gas introduction pipe 7 flows into the layered space 13. A plurality of inflow ports 14 are formed in the partition wall 12. The plurality of inlets 14 allow the gas that has passed through the layered space 13 to flow into the reaction chamber 11 from the periphery of the diffused material 2. For example, the inflow ports 14 are scattered all over the partition wall 12.

  The diffused material 2 is carried into the reaction chamber 11 from the opening of the reaction tube 10 in a state where the door 5 is opened. In the reaction chamber 11, the plurality of objects to be diffused 2 are held on the boat 3 so that all the objects to be diffused 2 are oriented so that one surface is perpendicular to the longitudinal direction of the reaction tube 10. It is assumed that the arrangement of the diffused material 2 in the reaction chamber 11 can be changed as appropriate. For example, the diffused material 2 may be arranged so that one surface thereof is parallel to the longitudinal direction of the reaction tube 10.

  The gas introduced into the reaction tube 10 from the gas introduction tube 7 passes through the layered space 13 inside the reaction tube 10 and flows into the reaction chamber 11 from each inlet 14. A gas flows into the reaction chamber 11 from the inlet 14 in each direction other than the side closed by the door 5. Thereby, the gas containing a diffusion source is supplied from various directions to the diffused object 2 heated by the heater 4.

  The thermal diffusion apparatus 1 introduces a diffusion source from a plurality of directions to the object to be diffused 2, so that the diffusion source has a uniform concentration compared to the case where the diffusion source is introduced into the reaction tube 10 from one direction. Can be dispersed. As a result, the thermal diffusion device 1 can supply a diffusion source with a uniform concentration to the object 2 to be diffused, and can form a diffusion layer having a uniform concentration and depth within the surface of the object 2 to be diffused. Become.

  Further, the heat diffusion device 1 can be sufficiently heated by the heater 4 by causing the gas introduced into the reaction tube 10 to flow into the layered space 13 near the outer surface of the reaction tube 10. Thereby, the thermal diffusion device 1 can supply a high-temperature gas including a diffusion source to the diffusion object 2, and can form a uniform diffusion layer on the diffusion object 2.

Embodiment 2. FIG.
FIG. 2 is a diagram illustrating a schematic configuration of the thermal diffusion device according to the second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and repeated description will be omitted as appropriate.

  The layered space 13 has a two-layer structure further divided into a first layer 21 and a second layer 22 by a partition wall 23. In the heat diffusing device 20 according to the second embodiment, the inside of the reaction tube 10 as a whole has a three-layer structure of a reaction chamber 11, a second layer 22 on the outside, and a first layer 21 on the outside. Has been.

  In the first layer 21, the gas introduced through the gas introduction tube 7 flows from the first end side of the reaction tube 10 to the second end side. The gas that has passed through the first layer 21 flows into the second layer 22 on the second end side of the reaction tube 10. The gas that has flowed into the second layer 22 flows into the reaction chamber 11 from each inlet 14.

  The gas introduced into the reaction tube 10 from the gas introduction tube 7 is heated by the heater 4 while passing through the first layer 21. The gas flowing into the reaction chamber 11 from the second layer 22 through the inflow port 14 is sufficiently heated by the heater 4 because the gas once flows in the first layer 21 in the longitudinal direction of the reaction tube 10. . Thereby, the thermal diffusion device 20 can supply a high-temperature gas including a diffusion source to the diffusion object 2, and a uniform diffusion layer can be formed on the diffusion object 2.

  As in the first embodiment, the thermal diffusion device 20 according to the second embodiment supplies a diffusion source with a uniform concentration to the diffused object 2, and the concentration and depth are within the plane of the diffused object 2. A uniform diffusion layer can be formed. In the first and second embodiments, the inlet 14 through which gas flows from the layered space 13 into the reaction chamber 11 may be any number, position as long as gas can be supplied from a plurality of directions to the diffused object 2. And size shall be arbitrary. The inflow port 14 may determine at least one of the number, the position, and the size according to the arrangement mode of the diffused material 2 in the reaction chamber 11.

  By applying the thermal diffusion devices 1 and 20 to the semiconductor device manufacturing process, it is possible to improve the uniformity of the concentration and depth of the diffusion layer of the semiconductor wafer, improve the characteristics of the semiconductor device, and reduce characteristic defects. Moreover, by applying the thermal diffusion devices 1 and 20, the cost can be reduced by reducing the volume of the raw material gas.

  As described above, the thermal diffusion device according to the present invention is useful when applied to a diffusion process for forming a diffusion layer on a semiconductor wafer.

DESCRIPTION OF SYMBOLS 1,20 Thermal diffusion apparatus 2 Object to be diffused 3 Boat 4 Heater 5 Door 6 Exhaust mechanism 7 Gas introduction pipe 10 Reaction pipe 11 Reaction chamber 12, 23 Partition wall 13 Layered space 14 Inlet 21 First layer 22 Second layer

Claims (2)

A reaction tube in which a reaction chamber for performing diffusion treatment on the object to be diffused is formed;
A heater for heating the diffused material from the periphery of the reaction tube;
A gas introduction pipe for introducing a gas including a diffusion source for forming a diffusion layer in the diffusion object heated by the heater into the reaction pipe,
The inside of the reaction tube is partitioned into the reaction chamber and a layered space in which the gas from the gas introduction tube flows around the reaction chamber,
A partition wall that partitions the reaction chamber and the layered space is formed with a plurality of inflow ports for allowing the gas that has passed through the layered space to flow into the reaction chamber around the diffused material. A thermal diffusion device characterized by the above.   The layered space is further directed from a first end portion of the reaction tube on the side where the gas introduction tube is provided to a second end portion of the reaction tube opposite to the first end portion. 2. A layer structure comprising: a first layer through which the gas flows; and a second layer through which the gas that has passed through the first layer flows into the inflow port. Heat diffusion equipment.

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