JPH11140650A - Rotary vapor phase thin film growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary vapor phase thin film growth device by which temp. difference in the plane of a wafer substrate generated at the time of vapor phase growth reaction, particularly, the temp. difference among the center part of the wafer, the outer peripheral part and the vicinity thereof, thermal stress generated thereby can be reduced as much as possible, and, therefore, wafer substrate laminated thin film free from lattice strips or the like and homogeneous in physical properties can be obtd. SOLUTION: Heat radiation directed to a wafer mounting part 6 from a heater 15 for heating is directly transmitted to a wafer substrate W through a through opening 1a and furthermore passes through the wafer mounting part 6 and is transmitted to the mounted wafer substrate W, and heat radiation directed to the bottom face part 4 from the heater 15 for heating is transmitted from the side face direction of the mounted wafer substrate through the inside wall face part 2 by a radiation heat inducing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase thin film growth apparatus, and more particularly, to an improved rotating apparatus for forming a thin film on a substrate surface such as a silicon wafer by CVD film growth or epitaxial film growth. The present invention relates to a vapor phase thin film growth apparatus.

[0002]

2. Description of the Related Art In recent years, a rotary type vapor phase thin film growth apparatus has many characteristics as compared with a batch type apparatus, and therefore its use has been widespread in the semiconductor industry. For example, in processing a large-diameter wafer, a high-speed rotating single-wafer type wafer epitaxial apparatus is becoming indispensable for forming a film having uniform in-plane characteristics.

In a conventional rotary vapor phase epitaxy apparatus, for example, as shown in FIG. 8, a gas introduction pipe 12 for supplying a raw material gas and a carrier gas into the furnace and a rectifier for regulating a gas flow are provided above the reaction furnace 11. A plate 13 is disposed, and a substrate holder 14 on which a wafer substrate W and the like are mounted, and a wafer substrate heating heater 15 disposed below the substrate holder 14 for heating the wafer substrate W and the like. And a rotating shaft 16 for rotating the substrate holder 14 are provided.
A motor (not shown) for driving the rotary shaft 16 to rotate and an exhaust pipe 17 for discharging exhaust gas containing unreacted gas in the reaction furnace are arranged below the lower part of the reactor. Further, the substrate holder 1
4 will be described in detail below (the lower side of the wafer substrate W).
The wafer substrate mounting holder 14 used in the furnace of the type that heats from the bottom is provided with an annular holder upper surface 14a and a concave shape along the inner peripheral edge thereof, and a through-opening 14 in the center.
c, and an annular bottom plate 14b having
The outer peripheral portion of the wafer substrate W is supported by 4b.

In order to vapor-grow a thin film on a wafer substrate W using such an apparatus, for example, first, a reaction gas, a carrier gas, and the like are supplied through a gas introduction pipe 12, and the momentum and the gas of the gas are supplied. The pressure distribution is made uniform, and a gas flow having a uniform flow velocity is caused to flow down through the current plate 13. The gas flow is supplied onto the wafer substrate W placed in the holder 14, and the wafer substrate W is heated by a heating heater 15 installed below while rotating the wafer substrate W together with the holder 14.
A thin film is vapor-phase grown on the surface. Exhaust gas containing unreacted gas is discharged from an exhaust port 17 provided below.

[0005]

When a predetermined heat treatment is performed while supporting the wafer substrate W by using such a conventional substrate holder 14, the wafer substrate supporting portion in the plane of the wafer substrate W is formed. And its neighboring area (hereinafter, referred to as
Since the manner of heat radiation received from the heating heater 15 is different between the region near the outer periphery of the wafer substrate and the other region, a temperature difference occurs in the wafer substrate surface, and thermal stress due to the temperature difference occurs. Occur. That is, while the central region of the wafer substrate W is a region that directly receives radiant heat from the through-opening 14c of the substrate holder 14, the annular bottom plate 14b
In the region near the outer peripheral edge of the wafer substrate in contact with the substrate, the radiant heat is transmitted indirectly through the annular bottom plate 14b. Further, a part of the heat transfer from the annular bottom plate 14b is dissipated from the outer peripheral edge of the substrate holder 14 and is lost, so that the temperature becomes lower. As a result, in the region near the outer peripheral edge of the wafer substrate, sufficient heat cannot be transmitted from the heating heater 15. For this reason, a temperature difference occurs between the central region or the like of the wafer substrate W and the region near the outer peripheral edge, and as a result, a slip occurs on the wafer substrate due to thermal stress.

In particular, since the width of the annular bottom plate 14b for supporting the wafer substrate W is very small, the temperature gradient in the wafer substrate surface in the vicinity of the portion becomes very large. In order to avoid such inconvenience of thermal stress distortion, holder 1
It is conceivable that this temperature difference is reduced by forming 4 from a transparent material. However, simply changing the material to a transparent material inevitably causes light reflection on the surface of the substrate holder 14 and heat absorption of the substrate holder 14 itself. However, a temperature difference still occurs, and the occurrence of slip of the wafer substrate cannot be suppressed.

When such a conventional wafer substrate holder is used, as described above, the generation of thermal stress may not only cause a lattice plane slip in the wafer substrate crystal but also reduce the temperature within the wafer substrate surface. Due to the non-uniform distribution, there is a technical problem that the thickness of the growing thin film becomes non-uniform, and as a result, various physical properties such as the electrical characteristics of the thin film also become non-uniform. For this reason, there has been a demand for the emergence of a rotary vapor phase thin film growth apparatus capable of reducing the temperature difference at the support portion of the wafer substrate as much as possible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems of the conventional apparatus, and minimizes a temperature difference between a central region or the like of a wafer substrate and a region near an outer peripheral edge. Accordingly, there is provided a rotary vapor phase thin film growth apparatus capable of obtaining a high-quality wafer-substrate laminated thin film having a uniform in-plane thickness and physical properties of the obtained growth thin film without occurrence of lattice plane slip or the like. It is intended for.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned technical problems, the present invention is directed to a reactor having a substrate holder for mounting and holding a wafer substrate and a heater for heating the wafer substrate below the substrate holder. In the rotary vapor phase thin film growth apparatus for flowing a reaction gas from above while rotating a wafer substrate together with a holder and growing a thin film on the surface thereof, the substrate holder is defined by an outer peripheral edge and an inner peripheral edge. An annular upper surface of the holder, an inner wall portion extending downward from the inner peripheral edge, a wafer mounting portion extending inward from the inner wall surface and having a through-opening at a central portion, and a lower portion extending from the outer peripheral edge of the upper surface of the holder. The heat radiation directed from the heating heater to the wafer mounting portion is directly transmitted to the wafer substrate through the through-opening, and the wafer mounting portion is also provided. Placed through The heat radiation transmitted to the heated wafer substrate and directed from the heating heater to the bottom portion is transmitted from the side of the wafer substrate placed through the inner wall portion by the radiation heat guiding means. That is the basic configuration.

Here, a part of the heat radiation directed from the wafer mounting portion to the outer bottom surface portion is transmitted from the side surface direction of the mounted wafer substrate through the inner wall surface portion. Preferably, the portion is provided with radiant heat guiding means so as to be transmitted to the wafer mounting portion, and the radiant heat guiding means includes an upper surface portion, an outer peripheral side surface portion of the wafer substrate holder,
It is desirable that the radiating heat reflecting surface is provided in an area defined by the inner wall surface and the bottom. Further, it is preferable that the radiant heat reflecting surface is installed so as to have an angle of 45 degrees with respect to the upper surface of the wafer substrate holder.

According to the present invention, a wafer substrate placed on a substrate holder is placed in a specific area within a wafer substrate surface to which radiation heat is not directly applied during heating (more specifically, a wafer in contact with a wafer mounting portion of the substrate holder). The area and the amount of heat radiation to be received are different between the area of the substrate) and the other area to which the radiant heat is directly applied during heating (the area of the wafer substrate corresponding to the through opening of the wafer mounting portion). Thermal stress occurs in the plane due to the temperature difference. For this reason, in order to solve the inconvenience in the conventional apparatus that the crystal thin film is likely to slip on the obtained thin film and to cause in-plane non-uniformity such as film thickness and physical properties, the radiant heat received by the bottom portion of the holder is solved. By providing a means for inducing radiant heat so as to be incident from the side surface of the wafer substrate via the inner wall surface, for example, a means for installing a reflection surface in a holder, a specific area (radiation) of the wafer substrate is provided. This compensates for the shortage of irradiation heat in the area of the wafer substrate that is not directly exposed to heat, and suppresses the generation of thermal stress caused by a temperature difference from other areas.

First, the in-plane temperature non-uniform distribution of the wafer substrate and the resulting thermal stress will be described below. The thermal stress due to the temperature distribution in the wafer substrate surface is generally represented by the following equation when considered in terms of radial and circumferential stress components.

[0013]

(Equation 1)

[0014]

(Equation 2)

Here, σr and σθ are respectively in the radial direction,
Circumferential stress component, T is a temperature distribution function in the wafer substrate surface, r is the radial coordinate of the wafer substrate, R is the radius of the wafer substrate, α and E are the linear thermal expansion coefficients of the wafer substrate material,
The elastic modulus.

On the other hand, as a simplified model, the temperature distribution in the wafer substrate surface is a quadratic curve continuous from the center to the periphery except for the vicinity of the wafer substrate mounting portion (supporting portion) (for example, FIG. ) Is indicated by a broken line). That is, when the temperature distribution function is approximated by the following equation (3), it can be expressed by T = T ₀ + ΔT (r / R) ² (3). Accordingly, when the thermal stress is obtained by substituting the above equation (3) into the above equations (1) and (2), the thermal stress becomes σr = αEΔT [1- (r / R) ² ] / 4 (4) σθ = ΑEΔT [1-3 (r / R) ² ] / 4 (5) Here, T ₀ is the temperature at the center of the wafer substrate, Δ
T is the temperature difference in the wafer substrate surface (strictly speaking, the temperature difference between the center and the periphery of the wafer substrate).

Then, the equivalent thermal stress σe is obtained from the stress components σr and σθ obtained from the equations (4) and (5), and the stress component σr
, Σθ, and the equivalent stress σe in the plane of the wafer substrate are shown in FIG. The equivalent thermal stress σe means a typical stress in a multiaxial stress state, and when expressed using σr and σθ, σe = (σr ² −σr × σθ + σθ ² ) ^1/2
It is represented by In the drawings, corresponding thermal stress expressed as Sigma] e _1, the vertical axis _{σe 1 / (αEΔT / 4)} , the horizontal axis represents the distance r / R from the wafer center.

In accordance with the above-described calculation formula, the temperature T is calculated from the center of the wafer substrate to the radius b as shown in FIG.
_When the temperature distribution ΔT in the region outside the radius b is constant and the temperature distribution ΔT is calculated in the case of a model represented by a quadratic curve with respect to the radial distance, the temperature distribution ΔT is the largest in the equivalent thermal stress in the wafer substrate surface The maximum equivalent thermal stress σe _max is larger than the value in the above case calculated by the equations (4) and (5). The result of the analysis is shown in FIG.

In the case of FIG. 2, b = 0.9, that is, assuming that the distance from the outer peripheral edge to the center of the wafer substrate is 1, a range corresponding to 1/10 of the total length 1 near the outer peripheral edge (1) Region) is in contact with the wafer mounting portion of the holder. The dotted line in the figure indicates the temperature distribution (FIG. 2 (a)) and the equivalent thermal stress (FIG. 2 (b)) of the above-described simplified model (when the contact portion is infinitely small and uniformly heated). Is shown. Here, the maximum equivalent thermal stress σ shown in FIG.
_Comparing the calculation results of e _1max and the maximum equivalent thermal stress σe _2max shown in FIG. 2, even if the in-plane temperature difference of the wafer substrate is the same, in the latter case, the heat difference is about 1.9 times that of the former. Stress, and the wafer substrate on the holder is actually heated,
It turns out that it receives a bigger thermal stress than expected.

FIG. 3 shows a change in the maximum equivalent thermal stress σe _max when the range (parameter b / R) of the support region of the wafer mounting portion is changed. In this figure, the vertical axis represents σe _max / (αEΔT / 4), and the horizontal axis represents b / R
Is shown. From this drawing, depending on the range of the supporting portion area of the wafer mounting portion, the equivalent thermal stress may be twice or more as compared with the case of the quadratic curve temperature distribution of Expression (3) (in the case of FIG. 1). You can see that.

From the above results, it is understood that it is extremely important to make the in-plane temperature distribution of the wafer substrate by heating as uniform as possible during the vapor phase growth. As described above, the present invention compensates for the loss of radiant heat and absorbed heat received at the peripheral portion of the holder by guiding the radiated heat received at the outer peripheral portion of the holder to the peripheral portion of the wafer substrate by reflection or the like. By doing so, a feature is that a temperature drop in the peripheral portion (support portion) of the wafer substrate is avoided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. Here, FIG.
FIG. 5 is a perspective view of an embodiment of a wafer substrate holder provided in the rotary vapor phase thin film growth apparatus of the present invention, and FIG. 5 is a partial sectional view of the wafer substrate holder shown in FIG. Also,
FIG. 6 is a schematic view showing a state of a transmission path of a heat flux from a heating heater, and FIG. 7 is a sectional view showing another example of the substrate holder of the present invention. Note that parts other than the substrate holder have the same configuration as the members shown in FIG. 8, and thus description thereof will be omitted. In the drawing, a holder 1 has an annular holder upper surface portion 3 located on an outer peripheral side portion of an inner wall surface portion 2, a bottom surface portion 4 of the holder, a holder outer peripheral side surface portion 5, and inward from the inner wall surface portion. A wafer mounting portion 6 which extends and has a through opening 1a at the center thereof. The outer peripheral side surface portion 5 of the holder 1 is held by another holding member (not shown).

In the wafer substrate mounting portion 6 of the substrate holder 1, a reflection surface 7 having an inclination angle of about 45 degrees with respect to the holder upper surface portion 3 as shown in FIG. I have. Radiation heat transmitted through the bottom surface portion 4 of the substrate holder 1 is reflected by the reflection surface 7, and most of the reflected heat is transmitted from the side surface of the wafer substrate W via the inner wall surface portion 2.
The peripheral portion of the wafer substrate is irradiated and received, and a part of the reflected heat is transmitted to the wafer substrate mounting portion 6, and the peripheral portion of the wafer substrate receives the heat from the lower surface side. This compensates for surface heat reflection at the wafer substrate mounting portion 6 and heat flux loss around the wafer substrate due to heat absorption by itself. FIG. 6 schematically shows the state of the transmission path of the heat flux from the heater 15.

As a material for forming the substrate holder 1 of the present invention, quartz glass, light transmissive alumina, or the like is used, and among these, transparent quartz glass is preferably used. The reason why the transparent quartz glass is used is that the transmittance of infrared rays is high. A specific example of a suitable transparent quartz glass is, for example, a commercial product (product number T2630) quartz glass manufactured by Toshiba Ceramics Corporation.

The substrate holder 1 according to the present invention may be made of a single material such as the transparent quartz glass, but the substrate holder 1 has a radiant heat guiding means 7 such as a reflection surface.
In particular, when the means is a reflection surface, a structure in which two members are combined is used, and the reflection surface is coated by a method such as coating a reflection film on the combined surface. More preferably, it is formed. Gold can be used as the reflective film to be coated, and can be formed by a known means such as vapor deposition. Further, a portion defined by the upper surface portion 3 and the outer peripheral side portion 5 above the radiant heat guiding means 7 is preferably formed of an opaque material. By using an opaque material, an infrared reflection effect can also be obtained. As this opaque material, for example, opaque quartz may be used, or another known material generally used as a material for forming this kind of holder 1 may be used.

As the radiant heat guiding means 7 in the present invention, the above-described radiant heat reflecting means by forming a reflecting surface is the simplest and most effective means, but is not necessarily limited thereto. As schematically shown in FIG. 2, the glass optical fiber bundle 9 and the like may be arranged and arranged from the bottom surface portion 4 of the substrate holder 1 to the inner wall surface portion 2 and the wafer mounting portion 6 to guide radiant heat rays. Further, the radiant heat ray may be guided using other infrared ray path changing means such as refraction.

In the case where the radiant heat reflecting means 7 by forming a reflecting surface is used, its reflecting surface is, for example, at an angle of 45 degrees with respect to the upper surface 3 of the wafer substrate holder 1 as shown in FIG. It is preferable to form and install it in a frustoconical (tapered) side shape so as to have a degree angle. Further, the surface of the holder bottom surface portion 4 and the surface of the inner wall surface portion 2 which receive the radiant heat from the lower heating heater 5 may be subjected to mirror polishing to improve the light transmittance of the radiant heat rays. preferable.

In the holder of the present invention, the radius of the inner wall portion 2 is set to be larger than the radius of the wafer substrate by about 0.5 to 2 mm, and the radius of the through-opening 1a at the central portion is defined as the radius of the wafer substrate. 0.7 to 0.
It is preferable to set the size to 95 times. The size of the outer peripheral edge of the holder is appropriately set in consideration of the overall structure of the device, the strength of the holder, and the like. As a reaction furnace constituting a main part of the rotary type vapor phase thin film growth apparatus of the present invention, a so-called vertical reaction furnace type known per se can be used except for the above-mentioned wafer holder constituent part. For example, a reactor whose entire configuration is shown in FIG. 8 is preferably used.

In order to form a thin film on a wafer substrate W by vapor phase growth using the rotary vapor phase thin film growth apparatus of the present invention, a reaction gas is supplied from an upper supply port 12 in a furnace via a rectifying plate 13. The wafer substrate W on the wafer mounting part 6 of the substrate holder 14 located below the rectifying plate 13 is caused to flow down together with the carrier gas, and the thin film is vapor-phased on the surface thereof while being rotated together with the substrate holder 1 under heating. By growing, a thin film can be formed.

[0030]

According to the rotary type vapor phase thin film growth apparatus of the present invention, the in-plane temperature difference of the wafer substrate generated at the time of the vapor phase growth reaction, which is a problem of the conventional apparatus, especially the central portion of the wafer substrate. The temperature difference between the region and the region near the outer periphery is reduced, and the resulting thermal stress can be reduced as much as possible. As a result, there is no lattice slip or the like, and the in-plane thickness and physical properties of the grown thin film are reduced. It is possible to obtain a high-quality wafer-substrate laminated thin film having a uniform quality.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a distribution of thermal stress (stress component and equivalent thermal stress) in a wafer surface in a quadratic curve temperature distribution model.

FIG. 2A is a diagram showing a change in temperature distribution in a b / R = 0.9 model, and FIG. 2B is a diagram showing a change in stress equivalent to heat.

FIG. 3 is a diagram showing a change in a maximum equivalent thermal stress.

FIG. 4 is a perspective view showing a shape of a substrate holder according to the present invention.

FIG. 5 is a view showing a cross section of a main part of the substrate holder shown in FIG. 4;

FIG. 6 is a schematic diagram showing a state of a transmission path of a heat flux from a heating heater.

FIG. 7 is a sectional view showing another example of the substrate holder of the present invention.

FIG. 8 is a schematic sectional view showing an example of a rotary vapor phase growth apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate holder 1a Through-opening 2 Inner wall surface part 3 Top surface part 4 Bottom part 5 Heating heater 6 Wafer substrate mounting part 7 Radiation heat induction means 9 Optical fiber bundle 11 Reaction furnace 12 Gas introduction pipe 13 Rectifier plate 14 Substrate Holder 15 Heating heater 16 Rotating shaft 17 Exhaust pipe W Wafer substrate

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Katsuhiro Chaki 30 Soya, Hadano-shi, Kanagawa Prefecture Toshiba Ceramics Co., Ltd.

Claims (4)

[Claims] 1. A reaction furnace comprising a substrate holder for mounting and holding a wafer substrate and a heater for heating the wafer substrate below the substrate holder, while rotating the wafer substrate together with the holder.
In a rotary vapor phase thin film growth apparatus that causes a reaction gas to flow down from above and grow a thin film on the surface thereof, the substrate holder is an annular holder upper surface defined by an outer peripheral edge and an inner peripheral edge, and from the inner peripheral edge. An inner wall portion extending downward, a wafer mounting portion extending inward from the inner wall surface and having a through opening in a central portion, an outer peripheral side portion extending downward from an outer peripheral edge of the upper surface of the holder, and a bottom portion. The heat radiation directed from the heating heater to the wafer mounting portion is:
The heat radiation transmitted directly to the wafer substrate through the through-opening and transmitted through the wafer mounting portion to the mounted wafer substrate, and directed from the heating heater to the bottom portion is radiant heat induction. A rotating vapor phase thin film growth apparatus, wherein the wafer is transmitted from a side direction of a wafer substrate placed through an inner wall portion by means. 2. A part of the heat radiation directed from the wafer mounting portion to an outer bottom surface portion is transmitted from a side direction of the mounted wafer substrate through an inner wall surface portion, and the other portion of the heat radiation. 2. The rotary vapor phase thin film growing apparatus according to claim 1, further comprising a radiant heat guide means for transmitting the heat to the wafer mounting portion. 3. The radiant heat guiding means is a radiant heat reflection surface provided in an area defined by an upper surface portion, an outer peripheral side surface portion, an inner wall surface portion, and a bottom surface portion of the wafer substrate holder. 3. The rotary vapor phase thin film growth apparatus according to claim 1 or 2. 4. The rotary vapor phase according to claim 3, wherein the radiant heat reflecting surface is installed at an angle of 45 degrees with respect to an upper surface of the wafer substrate holder. Thin film growth equipment.