JPH04252024A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To reduce a defect due to the abnormal outward appearance of an Si wafer by a method wherein, at a semiconductor manufacturing apparatus used to diffuse phosphorus to the Si wafer, a means to remove a phosphorus compound which is accumulated in a liquid state is provided near a gateway inside a core tube. CONSTITUTION:An Si wafer 6 which has been loaded on a boat 5 is put into a core tube 2 which has been heated to a high temperature by using a heater 1. After the Si wafer 6 has been put into the core tube 2, its temperature is raised further. After the temperature has been stabilized, a phosphorus compound which has been diluted with nitrogen gas via a gas introduction nozzle 4 by using a gas dilution 3 is introduced into the core tube 2; phosphorus is diffused to the Si wafer 6. The excess phosphorus compound which does not contribute to this diffusion comes into contact with the low-temperature open air at the outside of a drawing-out rod cap part 7, and is accumulated in a liquid state. A pump 11 for vacuum suction use is actuated; the compound is sucked by a phosphorus-compound suction part 9; the compound is stored in a phosphorus-compound storage tank 10 and is removed. After the compound has been removed, the boat 5 on which the Si wafer 6 has been loaded is taken out from the core tube, and a phosphorus diffusion treatment is finished.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus for diffusing phosphorus into a Si wafer.

0002

[Prior Art] A conventional device for diffusing phosphorus into Si wafers (hereinafter referred to as a phosphorus diffusion furnace) includes a heater 1 that heats a furnace core tube 2 to a high temperature, and a phosphorus diffusion furnace. It has a gas dilution 3 for supplying compounds and the like, a boat 5 for loading Si wafers 6, and a pull-out rod cap part 7 for preventing air from entering the furnace core tube 2.

Next, its operation will be explained. A boat 5 loaded with Si wafers 6 is placed in a furnace core tube 2 heated by a heater 1 . Si charged in the furnace core tube 2
After the wafer 6 is heated to a high temperature and the temperature is stabilized, a phosphorus compound diluted with nitrogen gas is introduced into the furnace core tube 2 from the gas dilution 3.

When the Si wafer 6 comes into contact with the phosphorus compound gas heated to a high temperature in the furnace core tube 2, phosphorus oxide is formed on the surface of the Si wafer 6, and phosphorus is diffused into the Si wafer 6. be exposed. The phosphorus compound introduced into the furnace core tube 2 is taken into the Si wafer 6, so that
In addition, since it is reduced due to adhesion to the furnace core tube 2, boat 5, etc., a concentration difference occurs between the nozzle 4 side in the furnace core tube 2 and the pull-out rod cap section 7 side, and as a result, after phosphorus diffusion The variation in layer resistance of the Si wafer 6 increases. As a countermeasure, the amount of phosphorus compound introduced must be large, at least 300 to 500% of the amount required for phosphorus diffusion in the Si wafer 6, so the excess phosphorus compound becomes liquid and accumulates on the outside of the pull-out rod cap portion 7. do.

[0005]

[Problems to be Solved by the Invention] In this conventional phosphorus diffusion furnace, in order to suppress variations in the layer resistance of the Si wafer 6 after phosphorus diffusion, the amount of the phosphorus compound introduced is adjusted to the amount necessary for the diffusion of the Si wafer 6. It is significantly more than that. Therefore, the excess phosphorus compound is cooled by the atmosphere outside the pull-out rod cap part 7 and accumulates in liquid form near the entrance and exit in the furnace core tube 2. After the diffusion of the Si wafers 6 is completed, when the boat 5 is unloaded, the boat wheels 8 etc. come into contact with the liquid phosphorus compound, causing the phosphorus compound to fly up and disintegrate the loaded Si.
There was a problem in that it adhered to the wafer 6 and caused an abnormal appearance of the Si wafer 6.

[0006]

[Means for Solving the Problems] The semiconductor manufacturing apparatus of the present invention removes liquid phosphorus compounds, etc., which have accumulated near the entrance and exit of the furnace core tube outside the pull-out rod cap, just before the boat is taken out of the furnace, during phosphorus diffusion of Si wafers. It has a phosphorus compound suction section for suctioning and removing, a vacuum pump, and a phosphorus compound storage tank.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a diagram showing Embodiment 1 of the present invention; FIG. 1(a) is a configuration diagram, FIG. 1(b) is a sectional view taken along line A-A in FIG. FIG. 2 is a detailed sectional view of the liquid phosphorus compound suction part shown in FIG.

[0008] Si wafers 6 loaded on a boat 5 are placed into a furnace core tube 2 heated to a high temperature by a heater 1 . After being placed in the furnace core tube 2, the Si wafer 6 is further heated and after the temperature stabilizes, a phosphorus compound diluted with nitrogen gas is passed from the gas dilution 3 through the gas introduction nozzle 4. Introduced into the furnace core tube 2, the Si wafer 6
Diffusion of phosphorus takes place. Further, the excess phosphorus compound that does not contribute to diffusion comes into contact with the low-temperature atmosphere outside the pull-out rod cap portion 7 and accumulates in a liquid state.

After the introduction of the phosphorus compound is completed and the temperature of the Si wafer 6 is lowered to a predetermined temperature, the vacuum suction pump 11
is activated, and the liquid phosphorus compound accumulated on the outside of the pull-out rod cap part 7 is sucked by the phosphorus compound suction part 9, stored in the phosphorus compound storage tank 10, and removed. After the removal of the phosphorus compound is completed, the boat 5 carrying the Si wafers 6 is taken out of the furnace, and the phosphorus diffusion process is completed.

Next, a second embodiment will be explained with reference to the drawings. FIG. 2 is a diagram showing a second embodiment, in which FIG. 2(a) is a configuration diagram and FIG. 2(b) is a sectional view taken along line BB in FIG. 2(a). In this embodiment, a furnace core tube phosphorus falling section 13 is provided in place of the phosphorus compound suction section 9 of the first embodiment. During phosphorus diffusion, phosphorus compounds, etc. that accumulate in liquid form on the outside of the pull-out rod cap part 7,
Since phosphorus flows from the furnace core tube phosphorus falling section 13 into the phosphorus receiving section 12, the structure is such that phosphorus compounds and the like do not remain in the furnace core tube 2.

[0011]

[Effects of the Invention] As explained above, the present invention provides a mechanism for suctioning the phosphorus compounds that accumulate on the outside of the pull-out rod cap, so that the phosphorus compounds that accumulate on the outside of the pull-out rod cap are removed. When a boat loaded with Si wafers is taken out of the furnace core tube, there is no risk that the wheels etc. will come into contact with liquid phosphorus compounds, and this has the effect of reducing defects due to abnormal appearance of Si wafers to 10% or less.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing Embodiment 1 of the present invention; FIG. 1(a) is a configuration diagram, FIG.
c) is a detailed cross-sectional view of the suction portion of the phosphorus compound accumulated in liquid form in Fig. 1(a).

FIG. 2 is a diagram showing a second embodiment; FIG. 2(a) is a configuration diagram, and FIG. 2(b) is a sectional view taken along line BB in FIG. 2(a).

FIG. 3 is a configuration diagram of a conventional semiconductor manufacturing apparatus.

[Explanation of symbols]

1 Heater 2 Furnace core tube 3 Gas dilution 4 Nozzle 5 Boat 6 Si wafer 7 Pull-out rod cap part 8 Boat wheels 9 Phosphorus compound suction part 10 Phosphorus compound storage tank 11 Vacuum suction pump 12 Phosphorus receiving part 13　　　Furnace core tube phosphor fall part

Claims (1)

[Claims] 1. A semiconductor manufacturing apparatus for diffusing phosphorus into a Si wafer, comprising means for removing phosphorus compounds that accumulate in liquid form near an entrance and exit in a furnace core tube.