JP3613099B2 - Vapor growth equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vapor phase growth apparatus in which a semiconductor wafer is mounted on a wafer holder disposed in a reaction chamber, and a thin film is formed on the surface of the semiconductor wafer by supplying gas into the reaction chamber.
[0002]
[Prior art]
As an epitaxial growth method on a silicon substrate, a vapor phase growth method, in particular, a chemical vapor deposition method (CVD method) is widely used. In the CVD method of silicon, a compound containing Si, for example, silicon tetrachloride, trichlorosilane, dichlorosilane, monosilane, etc. is sent onto a silicon substrate heated to about 1000 ° C., and reduced (or thermally decomposed) onto the substrate to form Si. Is precipitated.
[0003]
Among apparatuses for realizing such vapor phase growth, there is an apparatus in which a semiconductor wafer is mounted on a side surface of a wafer holder (susceptor) formed in a truncated polygonal pyramid shape. In this vapor phase growth apparatus, a plurality of gas injection nozzles for supplying gas into the reaction chamber are attached, and while rotating the wafer holder in the reaction chamber, a predetermined gas flows along the side surface of the wafer holder, By repeatedly passing the semiconductor wafer through the gas, a thin film is formed on the surface of the semiconductor wafer.
[0004]
Conventionally, in such a vapor phase growth apparatus, the direction of the gas injection nozzle and the flow rate ratio of the gas are adjusted so that a thin film is formed as uniformly as possible on the surface of the semiconductor wafer.
[0005]
[Problems to be solved by the invention]
However, in the conventional vapor phase growth apparatus described above, since the wafer holder on which the semiconductor wafer is mounted has a polygonal shape, a portion of the surface of the wafer holder with respect to the gas flowing in the axial direction of the wafer holder The gas flow on the surface of the semiconductor wafer changes depending on whether or not the corners pass and the film thickness unevenness is likely to occur in the thin film formed on the surface. Such film thickness unevenness mainly varies in the circumferential direction, so it is difficult to make the film thickness uniform by adjusting the gas direction and flow rate from the gas injection nozzle described above.
[0006]
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a vapor phase growth apparatus capable of uniformly growing a thin film on a semiconductor wafer.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a gas phase in which a semiconductor wafer is mounted on a wafer holder disposed in a reaction chamber and a thin film is formed on the surface of the semiconductor wafer by supplying gas into the reaction chamber. In the growth apparatus, drive means for rotating the wafer holder in the reaction chamber, and control means for changing the rotation speed of the wafer holder according to the growth rate distribution of the thin film in the circumferential direction of the wafer holder. The technology to prepare is adopted.
Further, the present invention provides the vapor phase growth apparatus according to claim 1, wherein the control means is a technique for changing a rotation speed of the wafer holder in accordance with a growth speed distribution of the thin film in the surface of the semiconductor wafer. Adopted.
Further, the present invention provides a vapor phase growth apparatus in which a semiconductor wafer is mounted on a wafer holder disposed in a reaction chamber, and a thin film is formed on the surface of the semiconductor wafer by supplying a gas into the reaction chamber. The wafer holder has an outer peripheral surface constituted by a plurality of plane portions on which the semiconductor wafer is mounted and corner portions between the plane portions adjacent to each other, and the gas is axially disposed in the reaction chamber. And a driving means for rotating the wafer holder in the reaction chamber, and when the plane portion of the wafer holder passes through the gas flow portion and when the corner portion passes , A technique is adopted that includes control means for changing the rotation speed of the wafer holder when the corner portion that tends to disturb the gas flow passes through the flow location .
The present invention can solve the above-described problems by adopting such a technique.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a vapor phase growth apparatus according to the present invention will be described with reference to the drawings. The vapor phase growth apparatus according to the present embodiment is a so-called cylinder type vapor phase growth apparatus, and includes a bell-shaped reaction chamber 10 (hereinafter referred to as a bell jar) made of quartz serving as a sealed space. A wafer holder (hereinafter referred to as a susceptor) 11 that rises and falls together with a lid that is openable and closable on the upper surface is suspended via a hanger 12.
[0009]
The susceptor 11 has an outer peripheral surface constituted by a plurality (six in this case) of flat surface portions 11a on which the semiconductor wafer W is mounted and corner portions 11b between the adjacent flat surface portions 11a, and has a polygonal shape (here, a regular hexagon). Are formed in a truncated polygonal pyramid shape having a top surface 11c and a bottom surface 11d. Further, the susceptor 11 is rotated in the bell jar 10 by the driving means 20 and the rotation speed thereof is adjusted by the control means 21. The control means 21 controls the entire apparatus including adjustment of the rotation speed of the susceptor 11.
[0010]
A heater (for example, an infrared copying heating source) 22 is provided around the bell jar 10, and the heater 22 raises the temperature of the semiconductor wafer W mounted on the side surface of the susceptor 11 to a predetermined reaction temperature. ing.
[0011]
In addition, a plurality of (two in this case) gas supply portions having gas injection nozzles 23 are provided in the upper portion of the bell jar 10 in order to guide the gas from the gas supply means 24 into the bell jar 10. The exhaust part 25 is provided so that the gas in the bell jar 10 may be discharged to the outside from below.
[0012]
FIG. 2 shows the state of gas flow near the top of the bell jar 10. In the present embodiment, the gas ejected from the two gas injection nozzles 23 passes over the susceptor 11 and comes into contact with the quartz rectifying member 30, and the flow is changed downward therefrom. Here, the location where the gas flows downward is defined as a flow location FA. Actually, since gas flows downward also from other locations, the flow location FA is a location where the gas flow rate is faster than other locations among the locations where the gas flows downward. Note that silicon tetrachloride, trichlorosilane, dichlorosilane, monosilane, or the like is used as a reaction gas for vapor phase growth.
[0013]
Next, the operation of the vapor phase growth apparatus of the present embodiment configured as described above, here, the operation of performing epitaxial deposition of silicon will be described.
In starting the film formation, the control means 21 shown in FIG. 1 first purges the interior of the bell jar 10 with hydrogen gas by the gas supply means 24 and rotates the susceptor 11 via the driving means 20 while the bell jar 10 is rotated by the heater 22. The temperature in the 10 chambers is raised to, for example, about 1200 ° C., and the semiconductor wafer W is uniformly heated at a desired process temperature. Subsequently, for example, a mixed gas of hydrogen chloride and hydrogen is supplied into the bell jar 10 by the gas supply means 24, the surface of the substrate is etched, and the inside of the bell jar 10 is purged again with hydrogen gas.
[0014]
After this etching process is completed, the control means 21 adds a silicon source gas such as silicon tetrachloride, trichlorosilane, dichlorosilane, or monosilane to the hydrogen gas that is a carrier gas by the gas supply means 24, and this mixed gas is supplied to the two gases. The gas is supplied into the bell jar 10 through the gas injection nozzle 23.
[0015]
The mixed gas injected from the gas injection nozzle 23 merges in the vicinity of the quartz rectifying member 30 and changes its flow downward along the inner wall of the bell jar 10 as shown in FIG. Then, a thin film (epitaxial layer) grows on the surface of the semiconductor wafer W by the semiconductor wafer W rotating together with the susceptor 11 repeatedly passing through the mixed gas of the flow location FA.
[0016]
By the way, in this apparatus, since the susceptor 11 on which the semiconductor wafer W is mounted has a truncated polygonal pyramid shape, when the flat portion 11a of the susceptor 11 is positioned at the flow point FA, and when the susceptor 11 is at the flow point FA. The flow of the mixed gas is different when the corner 11b is located.
[0017]
That is, as shown in FIG. 4 (a), when the flat portion 11a of the susceptor 11 is positioned at the flow location FA, the mixed gas flows downward smoothly and the reaction proceeds easily, whereas FIG. 4 (b). As shown in FIG. 4, when the corner 11b of the susceptor 11 is located at the flow point FA, the downward flow spreads laterally by the corner 11b. Increases the time of contact with a gas having a high flow rate and the growth rate of the thin film. Therefore, in the conventional vapor phase growth apparatus, the film thickness of the vapor phase formed on the semiconductor wafer W has a waveform as shown in FIG. 5, for example.
[0018]
Therefore, in the vapor phase growth apparatus of the present embodiment, the rotation speed of the susceptor 11 is changed by the control means 21 in accordance with the growth rate distribution of the thin film in the circumferential direction of the susceptor 11. That is, the control means 21 is based on the change in the thickness of the thin film when the susceptor 11 is rotated at a constant rotational speed, for example, a region having a thicker film than other regions (a region having a high growth rate of the thin film, for example, FIG. When the regions (s) and (u) shown in FIG. 5 pass through the flow point FA, the susceptor 11 is rotated at a high speed, and conversely, the region having a smaller film thickness (for example, the region (t) shown in FIG. 5). The susceptor 11 is rotated at a low speed when the susceptor 11 passes through the flow area FA, and the rotation speed of the susceptor 11 is changed according to the growth rate of the thin film for each circumferential region on the semiconductor wafer W. When the rotational speed when passing through the flow point FA becomes faster, the time of contact with the gas having a high flow rate becomes short, so that the thin film in the region becomes difficult to grow, and conversely, when the rotational speed becomes slow, the gas in the region has a high flow rate. Touching for a long time, the thin film grows faster than others. Therefore, it is possible to reduce variations in the growth rate of the thin film in the circumferential direction by changing the rotation speed of the susceptor 11 as described above as compared to when the susceptor 11 is rotated at a constant rotation speed.
[0019]
Furthermore, in order to suppress the influence of the gas flow by the corner portion 11b described above, the control means 21 determines whether the susceptor 11 has a difference between when the plane portion 11a passes through the gas flow point FA and when the corner portion 11b passes. Change the rotation speed. In the present embodiment, control is performed so that the rotation speed of the susceptor 11 is increased when the corner portion 11b that easily disturbs the gas flow passes through the flow point FA. Since the corner portion 11b quickly passes through the flow point FA, the turbulence of the gas flow is reduced, thereby reducing the film thickness unevenness caused by the turbulence of the gas flow.
[0020]
In the control means 21, the above speed change control is performed for each plane portion 11 a of the susceptor 11, so that a series of speed control is periodically repeated six times during one rotation of the susceptor 11.
[0021]
Then, by controlling the rotational speed of the susceptor 11 by the control means 21 in this way, the gas phase grows uniformly on the surface of the semiconductor wafer W, and a thin film (epitaxial layer) with little film thickness unevenness is formed. Is done.
[0022]
That is, according to the vapor phase growth apparatus of the present embodiment, since the rotation speed of the susceptor 11 is changed according to the growth rate distribution of the thin film in the circumferential direction of the susceptor 11, the film thickness unevenness in the circumferential direction can be reduced. . Thereby, a film thickness nonuniformity can be reduced and a thin film can be uniformly grown on the surface of the semiconductor wafer W.
[0023]
Further, since the rotational speed of the susceptor 11 is changed between when the plane portion 11a of the susceptor 11 passes and when the corner portion 11b passes through the gas flow point FA, it is possible to suppress the disturbance of the gas flow. Thereby, the film thickness unevenness caused by the gas flow disturbance can be reduced, and the thin film can be further uniformly grown on the surface of the semiconductor wafer W.
[0024]
The various shapes and combinations of the constituent members shown in the above-described embodiments are merely examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention.
[0025]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained. In the vapor phase growth apparatus according to the present invention , the rotational speed of the wafer holder is changed in accordance with the growth rate distribution of the thin film in the circumferential direction of the wafer holder. A thin film can be uniformly grown on the surface.
[0026]
In the vapor phase growth apparatus according to the present invention , the rotational speed of the wafer holder is changed in accordance with the growth rate distribution of the thin film in the surface of the semiconductor wafer. For example, the growth rate of the thin film is larger on the semiconductor wafer than the others. The growth rate of the thin film can be controlled for each predetermined region on the semiconductor wafer, such as shortening the contact time between the predetermined region and the gas to suppress the growth rate. Therefore, the film thickness unevenness of the thin film can be further reduced.
[0027]
In the vapor phase growth apparatus according to the present invention , in order to change the rotation speed of the wafer holder between when the plane portion of the wafer holder passes through the gas flow location and when the corner passes, It is possible to suppress the turbulence of the gas flow by controlling the turbulent corners so as to pass through the gas flow point quickly. Therefore, the film thickness unevenness caused by the gas flow disturbance can be reduced, and the thin film can be uniformly grown on the surface of the semiconductor wafer.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a vapor phase growth apparatus according to the present invention.
2 is a diagram showing a gas flow of the vapor phase growth apparatus of FIG. 1;
FIG. 3 is a diagram showing a gas flow of the vapor phase growth apparatus of FIG. 1;
FIG. 4 is a diagram showing a state where a plane portion and a corner portion of a susceptor pass through a gas flow location.
FIG. 5 is a diagram showing a change in film thickness of a thin film formed on the surface of a semiconductor wafer when a susceptor is rotated at a constant speed.
[Explanation of symbols]
W Semiconductor wafer FA Flow point 10 Bell jar (reaction chamber)
11 Susceptor (wafer holder)
11a Plane portion 11b Corner portion 20 Driving means 21 Control means 23 Gas injection nozzle

Claims (1)

In a vapor phase growth apparatus in which a semiconductor wafer is mounted on a wafer holder disposed in a reaction chamber, and a thin film is formed on the surface of the semiconductor wafer by supplying a gas into the reaction chamber,
The outer peripheral surface of the wafer holder is composed of a plurality of plane portions on which the semiconductor wafer is mounted and corner portions between the plane portions adjacent to each other.
In the reaction chamber, a flow point where the gas flows in the axial direction of the wafer holder is formed,
Driving means for rotating the wafer holder in the reaction chamber;
Depending on the growth rate distribution of the thin film in the circumferential direction of the wafer holding member, in the case the plane of the flow point of the previous SL gas the wafer carrier is that the corners passes and when passing the flow of the gas A vapor phase growth apparatus comprising: control means for changing a rotation speed of the wafer holder so that the rotation speed is increased when the corner portion that easily disturbs the flow passes through the flow location.

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