JP2009081185A - Vapor deposition apparatus and vapor deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor deposition apparatus including a heater for reducing dispersion in in-plane temperature distribution of a semiconductor substrate and increasing the uniformity of thickness of a film formed by the vapor deposition method on the semiconductor substrate, and to provide a vapor deposition method. <P>SOLUTION: The vapor deposition apparatus comprises a chamber 101, a gas supply section 102 for supplying a process gas working as a raw material for vapor deposition into the chamber 101, a heater 109 disposed in the chamber 101 and made of a resistive heating material having slits 111 tilted to the surface of the heater, and a gas exhaust section 105 for discharging the process gas from inside of the chamber 101. This can increase the uniformity in the in-plane temperature distribution of the wafer 103 to be heated by the heater 109. As the result, the thickness and quantity of the film formed by the vapor deposition method can be increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vapor phase growth apparatus and a vapor phase growth method, and more particularly to a vapor phase growth apparatus that improves the uniformity of temperature distribution in the surface of a semiconductor substrate, in which a semiconductor substrate is heated by a heater having slits formed therein. The present invention relates to a vapor deposition method.

Epitaxial growth technology that can control the film thickness and impurity concentration is used to manufacture high-performance semiconductor elements such as ultra-high-speed bipolar, ultra-high-speed CMOS, and power MOS. It has become indispensable.
In the production of high-performance semiconductor elements such as ultra-high speed bipolar, ultra-high speed CMOS, and power MOS, epitaxial growth technology capable of controlling the impurity concentration and film thickness is indispensable for improving the performance of the element. Yes.
For epitaxial growth in which a single crystal film is formed on a semiconductor substrate such as a silicon wafer, atmospheric pressure chemical vapor deposition is generally used, and in some cases, low pressure chemical vapor deposition (LPCVD) is used.
In these vapor phase growth methods, the inside of a vapor phase growth reactor in which a semiconductor substrate such as a silicon wafer is disposed is maintained at normal pressure (0.1 MPa (760 Torr)) or reduced pressure, and the semiconductor substrate is heated and rotated. In this state, a mixed gas of a source gas serving as a silicon source and a dopant gas containing a boron compound, a phosphorus compound, an arsenic compound, or the like is supplied into the vapor phase growth reactor. Then, a thermal decomposition reaction or hydrogen reduction reaction of the source gas is performed on the surface of the heated semiconductor substrate, and a crystal doped with a desired impurity such as boron (B), phosphorus (P), or arsenic (As). A film is formed. The characteristics of the crystal film formed here, such as film thickness and impurity concentration, depend on the temperature of the semiconductor substrate during vapor phase growth, so that the temperature during the vapor phase growth reaction is made uniform over the entire surface of the semiconductor substrate. It is always desired.

FIG. 8 is a top view showing the configuration of the heater 309 provided in the conventional vapor phase growth apparatus.
In order to ensure a long conductive path for generating heat due to a large electric resistance, the heater 309 is formed in a substantially concentric circle with a slit 311 formed perpendicular to the substantially horizontal surface of the resistance heating body. And it connects with the power supply mechanism which is not illustrated through the terminal parts 310a and 310b, and it heat | fever-generates by making the electric current of a predetermined magnitude | size conduct | electrically_connect. At this time, the slits 311 formed in the heater 309 are separated by a predetermined distance that does not discharge or short-circuit between the resistance heating bodies. (See Patent Document 1).
JP-A-10-208855

  The resistance heating type heater 309 described above has a resistance heating body that generates heat and a slit 311 that does not generate heat in the surface thereof. As a result, the temperature distribution of the semiconductor substrate to be heated varies, and the film thickness uniformity of the vapor-deposited film to be formed cannot be sufficiently improved.

In addition, in order to eliminate this variation in temperature distribution, a method of heating the semiconductor substrate 303 while rotating at high speed has been attempted. Thus, although the variation in temperature distribution is reduced to some extent as compared with the method of heating without rotating the semiconductor substrate 303, the temperature distribution of the semiconductor substrate 303 has not yet been made sufficiently uniform.
Therefore, the conventional vapor phase growth apparatus cannot produce a high-quality semiconductor substrate required for manufacturing a high-performance semiconductor element.

  The present invention has been made to overcome such problems, and includes a heater for improving uniformity of in-plane temperature distribution of a semiconductor substrate for vapor phase growth, and the thickness of the vapor phase growth film to be formed. There are provided a vapor phase growth apparatus and a vapor phase growth method capable of further improving the uniformity of the above.

The vapor phase growth apparatus of the present invention is
A chamber;
A gas supply unit for supplying a process gas, which is a raw material for vapor phase growth, into the chamber;
A heater composed of a resistance heating element disposed in the chamber and having a slit inclined with respect to the surface thereof;
A gas exhaust unit for exhausting process gas from the chamber;
It is characterized by providing.

  The above-mentioned resistance heating body is preferably made of silicon carbide, aluminum nitride or tungsten nitride as a base material.

  It is preferable that the heater satisfies d ≦ t / tan θ, where t is the thickness of the resistance heating element constituting the heater, d is the width of the slit, and θ is the inclination angle of the slit.

  The inclination angle θ of the slit formed in the heater is effective when 15 ° ≦ θ <90 ° (uniformity in the in-plane temperature distribution of the semiconductor substrate), and the experimental results are particularly in the range of 30 ° to 60 °. From this, it was found that the in-plane temperature distribution of the semiconductor substrate became uniform.

The vapor phase growth method of the present invention comprises:
Supplying a process gas, which is a raw material for vapor phase growth, into the chamber from a gas supply unit;
A step of heating the semiconductor substrate by a heater made of a resistance heating body formed in a chamber and having a slit inclined with respect to the surface thereof, and performing vapor phase growth on the semiconductor substrate;
And a step of exhausting the process gas left by the vapor phase growth from the chamber through a gas exhaust unit.

  With this configuration, the uniformity of the heat generation amount on the entire surface of the heater is improved, and variations in the in-plane temperature distribution of the semiconductor substrate heated by the heater are reduced. As a result, the uniformity of the film thickness of the vapor growth film formed on the semiconductor substrate can be improved.

Hereinafter, this embodiment will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration of a main part of a vapor phase growth apparatus 100 of the present embodiment.
The vapor phase growth apparatus 100 includes, for example, a chamber 101 that is a cylindrical hollow body made of metal, a source gas that is a silicon source that is a raw material for vapor phase growth inside the chamber 101, and a predetermined gas inside the chamber 101 A gas supply unit 102 for supplying a process gas which is a mixed gas with a dopant gas to which impurities are added is provided. The chamber 101 includes a rectifying plate 104 that rectifies the process gas supplied from the gas supply unit 102 and uniformly supplies the process gas to the entire surface of the wafer 103 that is an example of the semiconductor substrate disposed below. A gas exhaust unit 105 for exhausting the process gas in the chamber 101 containing the source gas after vapor phase growth on the surface of the wafer 103 to the outside is provided at the bottom of the chamber 101. The gas exhaust unit 105 is connected to a vacuum pump (not shown) installed outside the chamber 101 and maintains the inside of the chamber 101 at a predetermined vacuum level or a reduced pressure state.

The wafer 103 accommodated in the chamber 101 is placed on a ring-shaped holder 107 having a recess 106 formed on the upper part of a hollow cylindrical rotary drum 108 with the peripheral edge on the back surface grounded. Is done.
The concave portion 106 formed in the holder 107 restricts the movement of the mounted wafer 103 in the substantially horizontal direction, and stabilizes the vapor phase growth performed on the wafer 103.
The rotating drum 108 is connected to a rotating mechanism (not shown) provided outside the chamber 101 and rotates around the center line of the wafer 103 as a rotation axis. The holder 107 installed on the upper portion of the rotating drum 108 is rotated with the rotation of the rotating drum 108, and the wafer 103 placed on the holder 107 also rotates along with this.
Here, the hollow rotating drum 108 is connected to a vacuum pump (not shown) provided outside the chamber 101, and the inside of the rotating drum 108 can be maintained at a predetermined degree of vacuum or reduced pressure. Then, the wafer 103 is attracted and fixed to the holder 107, and a vapor phase growth film can be stably formed by vapor phase growth. On the other hand, if purge gas is supplied into the rotating drum 108 so that the inside and outside of the rotating drum 108 have substantially the same pressure, the flow of process gas into the rotating drum 108 is prevented, and the wafer 103 is attached to the holder by the adhesion of silicon crystals. It can be prevented from being fixed to 107.

FIG. 2 is a top view showing the configuration of the heater 109 of the present embodiment. FIG. 3 is an enlarged cross-sectional view showing the main part of the AA cross section of the heater 109 shown in FIG.
In the heater 109, for example, a slit 111 is formed so that a disk-shaped resistance heating body made of silicon carbide (SiC) is formed in a substantially concentric circle, and the heater 109 is disposed immediately below the wafer 103 in the rotating drum 108. The heater 109 is connected to a power supply mechanism (not shown) via the terminal portions 110a and 110b, and generates heat by conducting a current of a predetermined magnitude. At this time, the wafer 103 placed on the holder 107 is heated by the heater 109 while rotating, and is heated to a temperature at which vapor phase growth is performed. The slits 111 formed in the heater 109 not only form a predetermined conductive path, but are separated by a distance that does not discharge or short-circuit between the resistance heating bodies forming the heater 109.

As shown in FIG. 3, the slit 111 formed in the heater 109 of this embodiment is inclined by a predetermined angle θ with respect to the substantially horizontal surface of the heater 109, and opposite side walls are formed in parallel. Yes. Here, the inclination angle θ of the slit 111 takes an acute angle portion of the angles formed by the slit 111 and the substantially horizontal plane of the heater 109 intersecting.
The angle of the inward end portion 112 formed by the slit 111 is θ similarly because it is the tilt angle and the isotope angle of the slit 111. The slit 111 is formed, for example, with a predetermined substantially concentric circular conductive path in a state where a constant angle θ is always maintained with respect to the surface of a circular plate-shaped member made of silicon carbide having a predetermined thickness. It is formed by carrying out a wire cutting process. Therefore, the slit 111 forms a bowl-shaped inclined surface from the outer edge side of the heater 109 toward the center side. Here, as shown in FIG. 2, the slit 111 a formed so as to cut the center of the heater 109 may be inclined to the left or right with respect to the surface of the heater 109.
The substantially concentric circle described above is not a structure in which several true concentric circles are independently connected to each other, but a single conductive path that runs from the terminal portion 110a to the terminal portion 110b is formed, as shown in FIG. Shape. Further, the inward end portion 112 and the outward end portion 113 of the slit 111 formed in the heater 109 are not visible in the top view shown in FIG.

  The heater 109 is preferably made of silicon carbide, which is one of substances that generate heat when a current of a predetermined magnitude is conducted and does not contaminate the interior of the chamber 101. Further, the heater 109 can be made of either aluminum nitride (AlN) or tungsten nitride (WN).

The heater 109 has a relationship satisfying d <t / tan θ, where t is the thickness of the resistance heating element constituting the heater 109, d is the horizontal width of the slit 111, and θ is the inclination angle of the slit 111. Shape. That is, the horizontal component length of the inclined surface of the resistance heating body formed by the slit 111 is configured to be larger than the horizontal width of the slit 111. For this reason, the inward end portion 112 of the resistance heating body formed by the slit 111 is disposed below the resistance heating body adjacent to the center of the heater 109.
For example, when t = 1 cm, d = 0.2 cm, and θ = 60 degrees, since t / tan θ = 0.5 cm, the above-described positional relationship is achieved.

Therefore, when the heater 109 according to this embodiment is viewed from directly above, the lower side of the heater 109 is not seen through the slit 111. Therefore, the heater 109 does not have a portion that does not generate heat directly above, and the heat generation uniformity is improved. This is because, since the slit 111 is not perpendicular to the surface of the wafer 103 as in the prior art, heat is also generated from the resistance heater that forms the vertical inclined surface of the slit 111.
Moreover, since the relationship of d ≦ t / tan θ described above realizes a state where the lower side of the heater 109 is not seen through when d = t / tan θ, the characteristics of the present embodiment can be exhibited. However, in the case of d <t / tan θ, since the overlapping region of the end portion of the resistance heating body is large, the variation in the radiant heat emitted from the heater 109 is further reduced. For this reason, in order to obtain the better effect of this embodiment, it is desirable that d <t / tan θ.
Further, the angle θ of the inward end portion 112 is too sharp at the front end portion of the inward end portion 112, the electrical durability and physical strength as a resistance heating body are not impaired, and the in-plane temperature distribution of the wafer 103 is obtained. It is desirable that it is formed at 15 degrees or more and less than 90 degrees, which has an effect on uniformity of the film. In particular, in the range of 30 to 60 degrees, it was found from the experimental results that the in-plane temperature distribution of the wafer 103 is uniform.

FIG. 4 is an enlarged cross-sectional view showing the main parts of the wafer 103 and the heater 109 of this embodiment. FIG. 5 is a diagram showing the in-plane temperature distribution of the wafer 103 of the present embodiment.
The wafer 103 is heated by the heater 109 while rotating as the holder 107 rotates at a high speed by a rotation mechanism (not shown).
At this time, the region from the point P _1b to the point P _{1c and} the region from the point P _1d to the point P _{1e on} the wafer 103 correspond to the resistance heating body, and thus the temperature is raised to a predetermined temperature T ₁ shown in FIG. .
The region from the point P _1a to the point P _{1b and} the region from the point P _1c to the point P _{1d on} the wafer 103 are affected by heat generated from the portion including the slit 111 formed in the heater 109, and are shown in FIG. to temperature _{T 2} is heated. Here, when the variation T ₁ -T ₂ in the in-plane temperature distribution of the wafer 103 generated in the two regions described above is compared with the variation in the in-plane temperature distribution of the semiconductor substrate 303 of the conventional vapor phase growth apparatus, T 1 _From experimental results, it was found that _1- T ₂ falls within a range approximately 50% narrower than that of the conventional _one . That is, the heater 109 of this embodiment can improve the uniformity of the in-plane temperature distribution of the wafer 103 to be heated by about 50%.

Then, the process gas supplied from the gas supply unit 102 is uniformly supplied to the wafer 103 heated by the heater 109 described above via the rectifying plate 104, thereby performing vapor phase growth. Then, the process gas including the raw material gas subjected to the vapor phase growth is exhausted from a gas exhaust unit 105 connected to a vacuum pump (not shown).
By repeating the above-described procedure repeatedly for a predetermined time, a vapor phase growth film with improved film thickness uniformity can be formed. Further, if the temperature distribution in the wafer 103 plane is uniform, crystal defects are less likely to occur during the deposition of the vapor growth film, and the quality of the produced wafer can be improved.
As described above, the above-described various advantages can be obtained by overcoming the problems related to the temperature distribution of the wafer 103 during the vapor phase growth reaction.

Next, another example of the heater 209 will be described.
FIG. 6 is an enlarged cross-sectional view showing a main part of a heater 209 of another example of the present embodiment.
The heater 209 is configured by a resistance heating body in which a slit 211 inclined downward from the center of the heater 209 toward the outer edge is formed.
Like the heater 109, the slit 211 is a predetermined substantially concentric circular shape of a silicon carbide plate-shaped member having a predetermined angle θ with respect to the substantially horizontal surface. It is formed by wire cutting so that a conductive path is formed. Further, the angle of the outward end 213 formed by the slit 211 is θ similarly because it is the tilt angle and the isotope angle of the slit 211. Therefore, the slit 211 formed in the heater 209 forms an inclined surface that spreads from the center of the heater 209 toward the outer edge.

Similarly to the heater 109, the heater 209 has a thickness of the resistance heating member constituting the heater 209 t, the horizontal width of the slit 211 is d, and the inclination angle of the slit 211 is θ, d <t / This is a shape that satisfies the relationship tanθ.
That is, the heater 209 has substantially the same shape as that obtained by inverting the top of the heater 109.

FIG. 7 is an enlarged cross-sectional view showing the main parts of the wafer 103 and the heater 209.
The regions from the point P _2b to the point P _{2c and} the region from the point P _2d to the point P _2e of the wafer 103 heated by the heater 209 correspond to the resistance heating body, as in the case of the heater 109 shown in FIG. It is heated to a predetermined temperature T _1.
The region from the point P _2a to the point P _{2b and} the region from the point P _2c to the point P _{2d on} the wafer 103 are affected by heat generated from the portion including the slit 211 formed in the heater 209, and reach the temperature T _2. The temperature is raised.
Accordingly, the heater 209 can improve the uniformity of the in-plane temperature distribution of the wafer 103 by about 50% as compared with the case where the vapor phase growth is performed by a conventional vapor phase growth apparatus, in a manner similar to the heater 109.

  In this way, the slit formed in the heater is inclined by a predetermined angle with respect to the surface of the heater, and the inward end or the outward end formed by the slit in the resistance heating body is adjacent to the adjacent resistance heating body. If the configuration is located below, the uniformity of the heat generation can be improved over the entire surface of the heater. Then, the variation in temperature distribution generated in the surface of the wafer is weakened, and a vapor deposition film having a high quality and a uniform film thickness can be formed.

The embodiment has been described above with reference to specific examples. The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.
The present invention has been described with respect to an epitaxial growth apparatus as an example of a vapor phase growth apparatus. However, the present invention is not limited to this, and any apparatus for vapor phase growth of a predetermined vapor growth film on the wafer surface may be used. For example, an apparatus for the purpose of growing a polysilicon film may be used.

  Furthermore, in the present invention, a substantially concentric circular heater is used, but a resistance heating body is formed so that there is no region that does not generate heat on the entire surface of the heater, even if it has other shapes such as a spiral type or a comb type. If it does, the same effect can be acquired.

  Furthermore, although descriptions of parts that are not directly required for the present invention, such as apparatus configuration and control method, have been omitted, the required apparatus configuration and control method can be selected and used as appropriate. .

  In addition, all the vapor phase growth apparatuses that include the elements of the present invention and can be appropriately modified by those skilled in the art, and the shapes of the respective members are included in the scope of the present invention.

It is sectional drawing which shows the structure of the principal part of the vapor phase growth apparatus of embodiment of this invention. It is a top view which shows the structure of the heater of embodiment of this invention. It is an expanded sectional view which shows the principal part of the AA cross section of the heater shown in FIG. It is an expanded sectional view which shows the principal part of the cross-sectional shape of the wafer and heater of embodiment of this invention. It is a figure which shows the in-plane temperature distribution of the wafer of embodiment of this invention. It is an expanded sectional view showing the important section of the heater of other examples of the embodiment of the present invention. It is an expanded sectional view which shows the principal part of the wafer of embodiment of this invention, and the heater of another example. It is a top view which shows the structure of the heater with which the conventional vapor phase growth apparatus was equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Vapor growth apparatus 101 ... Chamber 102 ... Gas supply part 103 ... Wafer 104 ... Current plate 105 ... Gas exhaust part 106 ... Recessed part 107 ... Holder 108 ... Rotating drum 109, 209 ... Heater 110a, 110b ... Terminal part 111, 211 ... Slit 112 ... Inward end 113, 213 ... Outward end θ ... Tilt angle

Claims (5)

A chamber;
A gas supply unit for supplying a process gas which is a raw material for vapor phase growth into the chamber;
A heater composed of a resistance heating element disposed in the chamber and formed with a slit inclined with respect to the surface thereof;
A gas exhaust unit for exhausting the process gas from the chamber;
A vapor phase growth apparatus comprising:   2. The vapor phase growth apparatus according to claim 1, wherein the resistance heating body uses silicon carbide, aluminum nitride, or tungsten nitride as a base material.   The heater satisfies d ≦ t / tan θ, where t is the thickness of the resistance heating element constituting the heater, d is the width of the slit, and θ is the inclination angle of the slit. The vapor phase growth apparatus according to claim 2.   4. The vapor phase growth apparatus according to claim 3, wherein an inclination angle θ of the slit formed in the heater is 15 degrees ≦ θ <90 degrees. Supplying a process gas, which is a raw material for vapor phase growth, into the chamber from a gas supply unit;
A step of heating the semiconductor substrate by a heater made of a resistance heating body formed in a chamber and having a slit inclined with respect to the surface thereof, and performing vapor phase growth on the semiconductor substrate;
And a step of exhausting the process gas left by the vapor phase growth from the chamber through a gas exhaust unit.

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