JPH0468522A - Vertical heat treatment device - Google Patents

Abstract

PURPOSE:To improve sectional heat equalization property of a treatment object and to realize in-plane uniformity of a high density element by making treatment gas flow inside a vertical reaction tube which contains a plurality of treatment objects for pre-heating and by injecting treatment gas to the treatment objects thereafter. CONSTITUTION:When a wafer 19 is mounted on a specified position of a boat 20 and is transferred into a reaction tube 11, the tube 11 is heated to a set temperature by a heater 17. A clearance is provided to an outer peripheral wall of the reaction tube 11 to arrange an outer tube 12 coaxially and gas distribution means 13 is provided to the inside of the clearance; then, treatment gas supplied to a gas supply port 15 rises and flows in laminar flow uniformly through gas distribution holes 14a to 14e provided inside a clearance between the reaction tube 11 and the outer tube 12. Since treatment gas is pre-heated uniformly by the heater 17 and gas whose temperature is close to a gas temperature inside the reaction tube 11 is introduced, generation of downflow is reduced and a treatment gas temperature is approximately the same in any places in a plane of the wafer 19. Thereby, it is possible to improve sectional heat equalization property and to realize in-plane uniformity of a high density element.

Description

[Detailed description of the invention]

"Purpose of invention"

[Industrial application field]

The present invention relates to a vertical heat treatment apparatus.

[Conventional technology and its issues 1] In recent years, with the increase in the degree of integration of LSI, for example, 4MDRA
The minimum design width of M has become less than 1 μm, and the thickness of the gate oxide film has also become less than 200 Å. In particular, the gate oxide film of 16M DRAM is becoming thinner to 100 Å or less. When the film thickness becomes thin in this manner, it becomes extremely difficult to meet the requirement for in-plane uniformity of the film thickness on the semiconductor wafer. In order to meet this in-plane uniformity, it is necessary to make the processing conditions on the semiconductor wafer uniform, and in particular, it is extremely important to make the temperature conditions uniform. Usually, vertical heat treatment furnaces can reduce the temperature gradient in the axial direction of the processing furnace compared to horizontal heat treatment furnaces, and are advantageous for manufacturing high-density elements, so there is a recent trend of adopting vertical heat treatment furnaces. It is in. In a conventional vertical heat treatment furnace, for example, when semiconductor wafers are carried into the reaction tube of an oxidation furnace or diffusion furnace for heat treatment, a processing boat carrying a large number of wafers at predetermined intervals in the vertical direction is used. is carried into a reaction tube via a carrying-out/carrying mechanism, and a processing gas is supplied into this tube to carry out heat treatment. In this case, as a means for supplying the processing gas into the tube, as shown in FIG. The processing gas is made to flow from the inlet 4 through the flow path 10 into the interior through the inflow hole 9 provided at the upper end of the reaction tube 1, and to be exhausted from the exhaust port 5 provided at the bottom of the reaction tube 1. On the other hand, processing boats 7 loaded with a large number of semiconductor wafers 8 at predetermined intervals in the longitudinal direction are provided so as to be able to be carried into the reaction tube 1 via the boat elevator 6, and The semiconductor wafer 8 is heated by a heater 3 provided in the wafer 3 to perform heat treatment on the semiconductor wafer 8. The inside of this reaction tube 1 is normally heated to about 900 to 1200°C, and the processing gas is supplied from the inlet 4 to the flow path 1.
It flows into the inside of the reaction tube 1 through the inlet hole 9 provided at the upper end of the reaction tube 1 through the tube. In this case, the processing gas rises unevenly in the region of the flow path 1o near the inlet 4, and the processing gas flows in an uneven state, resulting in an uneven temperature distribution near the gas inlet in the reaction tube 1. As a result, cross-sectional thermal uniformity within the tube deteriorates, resulting in problems such as non-uniform temperature distribution within the wafer surface. The present invention was developed in two ways to solve the above-mentioned conventional problems, and by uniformly introducing the processing gas in a laminar flow state and uniformly preheating the processing gas, it is possible to improve the cross-sectional thermal uniformity of the object to be processed. The purpose is to improve the in-plane uniformity of high-density devices. "Structure of the Invention" [Means for Solving the Problems 1] In order to achieve the above object, 1 the present invention performs heat treatment by introducing a processing gas into a vertical reaction tube containing a plurality of objects to be processed. In the vertical heat treatment apparatus, the processing gas is caused to flow into the heat treatment temperature atmosphere of the object to be processed provided in the reaction tube to preheat it, and then the processing gas is caused to flow into the object to be processed. be. [Function] Therefore, according to the present invention, the introduced processing gas is introduced through the gas distribution means provided in the gap between the reaction tube and the outer tube, so that the processing gas is uniformly distributed in the gap in a laminar flow state. During this time, the processing gas is preheated by heat from the heater and then introduced into the reaction tube.
The introduced processing gas is uniformly preheated by the heater and the gas is introduced at a temperature close to the gas temperature in the reaction tube, so it is less likely to cause a downward flow after being introduced into the reaction tube, and the tube Radial diffusion takes place, improving cross-sectional heat uniformity. [Example 1] Hereinafter, an example of a vertical heat treatment apparatus according to the present invention will be described with reference to the drawings. In FIG. 1, a reaction tube 11 is formed of quartz glass into a cylindrical shape, and its axial direction is vertical, thereby forming a vertical heat treatment section. A cylindrical outer tube 12 made of quartz glass is coaxially arranged in a gap between the outer circumferential wall of the reaction tube 11, and a ring pipe 13 made of quartz glass is placed in the vicinity of the gas supply port 15 within this gap. The gas distribution hole 14a is fixed to the ring pipe 13.
A plurality of gas distribution means are formed by forming a plurality of gas distribution means 14e to 14e. The gas distribution holes 14a to 14e are connected to the gas supply port 1.
The distance between the distribution holes becomes larger as the region approaches the vicinity of 5, and the distribution holes are formed to be smaller. The distribution holes are not limited to the above example, and may be formed so that the distribution holes become denser to sparser as they approach the region near the gas supply port 15. Further, a cylindrical heater 1 is provided around the outer periphery of the reaction tube 11.
7 is provided, and the inside of the reaction tube 11 is, for example, 900 to 1
Oxidation and diffusion treatments are performed by heating to about 200°C. The reaction tube 11 has an open lower end and is vertically supported so that a boat 20 carrying a large number of objects to be processed, such as semiconductor wafers 19, horizontally and spaced apart in the vertical direction can be carried in and out. This boat 20 is vertically supported by a heat insulating cylinder 21, the heat insulating cylinder 21 is supported by a boat elevator 18, and the boat 20 can be carried in and out by driving the boat elevator 18 up and down, and the flange 18 of the boat elevator 18
The lower end opening of the reaction tube 11 is sealed with a. Further, a gas exhaust pipe 16 for exhausting processing gas from the lower end of the reaction tube 11 is connected to the reaction tube 11.
A buffer plate 22 having a large number of inflow holes 23 is provided at the upper end of the buffer plate 22 . That is, the reaction gas flowing in from the gas supply port 15 flows upward between the outer tube 12 and the outer wall of the reaction tube 11 via the gas distribution holes 14a, 14b, and so on. The exhaust hole 1 is arranged so that the reaction gas is introduced into the reaction tube 11 from the inflow hole 23 that is
6 is provided. Next, the operation of the above embodiment will be explained. For example, a case where an oxide film is formed on the semiconductor wafer 19 will be described. When the wafer ]-9 is loaded in a predetermined position on the boat 20 and carried into the reaction tube 11, the tube 1
1 is heated to a set temperature by a heater 17. and,
Since the outer tube 12 is disposed coaxially with a gap provided to the outer peripheral wall of the reaction tube 11, and the gas distribution means 13 is provided within this gap, the processing gas supplied to the gas supply port 15 can be used for reaction. Tube 11 and outer tube 1
2, the processing gas rises uniformly in a laminar flow state and flows uniformly through the gas distribution holes 14a to 14e provided in the gaps between the two. Since the gas having a similar temperature is introduced, a downward flow is less likely to occur after being introduced into the reaction tube 11. Therefore, the formation of a downward flow caused by a temperature difference as in the conventional case is reduced, and the processing gas is sufficiently diffused in the radial direction and descends. are almost the same, and the in-plane uniformity of the wafer 19 is improved. In the above embodiment, an example of a double pipe structure was explained, but
The present invention is not limited to this example, and any means may be used as long as all the processing gases are equally preheated and then flowed into the object to be processed. "Effects of the Invention" As is clear from the above, the present invention has the following excellent effects. In other words, when the processing gas is uniformly introduced in a laminar flow state, the processing gas uniformly preheated at the processing temperature experienced by the wafer is introduced into the reaction tube, thereby improving cross-sectional thermal uniformity and achieving high density. There are effects such as being able to improve the in-plane uniformity of the element.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a sectional view showing an embodiment of the vertical heat treatment apparatus of the present invention, FIG. 2 is an enlarged sectional view taken along the line A- in the same example, and FIG. FIG. 2 is a sectional view showing a conventional example. Fig. 1 11... Reaction tube 12... Outer tube 13... Gas distribution means 17... Heater Fig.

Claims (1)

[Claims] (1) In a vertical heat treatment device that performs heat treatment by introducing a processing gas into a vertical reaction tube containing a plurality of objects to be processed, the processing is carried out at the temperature atmosphere for the heat treatment of the objects provided in the reaction tube. A vertical heat treatment apparatus characterized in that a processing gas is caused to flow into the object to be processed after preheating it by flowing the gas.