JPH0815143B2 - Method for manufacturing 3C-SiC semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a Si (silicon) substrate and 3C (Cubic) -SiC.
The present invention relates to a method for manufacturing a 3C-SiC semiconductor device having a 3C-SiC carbonization buffer layer between a (silicon carbide) single crystal.

[Conventional technology]

As shown in FIG. 4, the 3C-SiC semiconductor device has a structure in which a 3C-SiC carbonization buffer layer 2 is formed on a Si substrate 1 and then a desired 3C-SiC single crystal film 3 is formed.

The carbonized buffer layer is formed in this way if the 3C-SiC single crystal is directly formed on the Si substrate and the Si substrate and the 3C-SiC single crystal are formed.
Due to the difference in lattice constant from C-SiC single crystal, 3C-SiC
This is because lattice defects are likely to occur in the single crystal. Therefore, the formation of the carbonization buffer layer prevents the lattice defects from occurring.

[Problems to be solved by the invention]

By the way, the above 3C-SiC semiconductor device is
3C when growing using the al Vapor Deposition method
The substrate temperatures when forming the -SiC carbonization buffer layer 2 and the 3C-SiC single crystal 3 are as high as 1360 ° C and 1350 ° C, respectively.

Therefore, impurities from the reaction system are easily incorporated into the 3C-SiC carbonization buffer layer 2 and the 3C-SiC single crystal 3.

Further, since the temperature of the Si substrate 1 is close to its melting point (1420 ° C.), lattice defects such as slip lines occur in the Si substrate 1 and the semiconductor device is apt to deteriorate.

This problem can be solved by lowering the substrate temperature, but when the substrate temperature is lowered, if the growth rate is increased, the growth film becomes twinned or polycrystalline, and 3C-SiC single crystal cannot be grown, In order to grow a 3C-SiC single crystal, the growth rate must be slowed down. Therefore, thick 3C-SiC
It takes a long time to form a single crystal, which is disadvantageous.

In addition, when the substrate temperature is low, a lattice defect due to a difference in lattice constant is likely to occur.

Therefore, in the case of the CVD method, it is not possible to manufacture a good quality 3C-SiC semiconductor device having no lattice defects simply by lowering the substrate temperature.

The present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a 3C-SiC semiconductor device having no lattice defect.

[Means for solving problems]

The present invention, the reaction atmosphere is a high vacuum atmosphere, the hydrocarbon gas and silicon are reacted in the atmosphere, SiC of the reaction product is formed into a layer on a Si substrate of relatively low temperature 3C- Manufactures SiC semiconductor devices.

That is, the method for manufacturing a 3C-SiC semiconductor device according to the present invention is a method for manufacturing a 3C-SiC semiconductor device having a 3C-SiC carbonization buffer layer between a Si substrate and a 3C-SiC single crystal,
Hydrocarbon gas and Si are reacted in a reaction chamber held in a high vacuum to form a 3C-SiC carbonization buffer layer on the Si substrate in the reaction chamber, and then the temperature of the Si substrate is raised to 3C- Si
After the C single crystal buffer layer is formed, the temperature of the Si substrate is further raised to form the 3C-SiC single crystal at a faster rate than when forming the 3C-SiC single crystal buffer layer.

〔Example〕

The present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the present invention. In the figure, reference numeral 10 denotes a bell-shaped reaction chamber of a chemical vapor line device. A part of the peripheral surface of the reaction chamber 10 is opened, and an insertion chamber 11 for inserting and removing the substrate is provided outside the opening.
Is evacuated to a high degree of vacuum by a pump (not shown). Si inserted into the reaction chamber 10 from the insertion chamber 11
The substrate 1 is attached to a substrate holder 13 whose height and horizontal rotation are controlled by a manipulator 14 provided on the ceiling of the reaction chamber 10 and set at a predetermined position in a predetermined direction. It can be taken out of the reaction chamber. A heater (not shown) is provided on the portion of the substrate holder 13 where the Si substrate 1 is attached, and the Si substrate 1 is heated to a predetermined temperature by this heater.

The reaction chamber 10 in the direction orthogonal to the reaction surface of the set Si substrate 1 is opened, one end of a cylinder is attached to the opening, and the other end is sealed with a lid, and the lid is Knudsen.
A cell 12 and a gas ejection nozzle 15 are provided. The tip of the nozzle 15 is inserted into the reaction chamber 10 so that the direction of gas ejection is
It faces the reaction surface of the Si substrate 1.

The base end of the nozzle 15 is connected to a gas tank (not shown) via a pipe, and the gas tank has a high-purity hydrocarbon gas,
For example, acetylene gas with a purity of 5nine is stored.

A crucible 17 is provided immediately below the tip of the nozzle 15 and the Si substrate 1 facing each other. The crucible 17 stores, for example, high-purity silicon having a purity of 10 nine. Crucible 17
In the vicinity of which is provided an electron beam generator 16, an electron beam generator 16 is an electronic (e ^-) which collide in the silicon in the crucible 17 by generating.

An electron beam generator 18 is provided on the peripheral surface of the reaction chamber 10 so that the electron beam emission port is inserted into the reaction chamber and the emission direction is directed toward the silicon substrate 1. The screen 18 is provided on the inner wall of the reaction chamber 10.
a is provided so that a diffraction line passing through the Si substrate 1 can be captured. The electron beam generator 18 and the screen 18a constitute an electron beam diffractometer, and the electron beam diffractometer detects the surface state of the growth film and the like.

Further, a molecular beam intensity measuring device (not shown) for measuring the molecular beam intensity in the vicinity of the substrate holder 13 and a mass spectrometer 19 are provided on the peripheral surface of the reaction chamber 10, and the mass spectrometer 19 is the reaction chamber. This is to confirm the existence of molecules, atoms, etc. in.

The manufacturing method of the present invention using the apparatus thus configured will be described below.

First, insert the substrate holder 13 into the insertion chamber with the manipulator 14.
The substrate is moved to a position where the substrate can be mounted in the vicinity of 11, and the Si substrate 1 is inserted from the insertion chamber 11 and mounted on the substrate holder 13. After that, the substrate holder 13 is moved and set by the manipulator 14, and then a not shown hump is operated to activate the reaction chamber.
The inside of 10 and the insertion chamber 11 is evacuated.

After that, when the predetermined vacuum degree is reached, the heater (not shown) of the substrate holder 13 is energized to start heating the Si substrate 1. Si
When the temperature of the substrate 1 reaches 1100 ° C., the temperature is maintained for a while to clean the surface of the Si substrate 1 (first step).

Then, the substrate temperature is lowered to stabilize the carbonization temperature.
The substrate temperature was maintained at a certain constant temperature of 750 ° C. to 820 ° C., and acetylene gas was introduced into the reaction chamber 10 through the nozzle 15 to adjust the acetylene gas pressure to 7 × 10 ⁻⁶ Torr. This state is maintained for 5 minutes (second step). As a result, as shown in FIG. 2, the 3C-SiC carbonization buffer layer 2 grows on the Si substrate 1.

The composition of the 3C-SiC carbonized buffer layer 2 is different at each position in the thickness direction, but the upper surface layer is a single crystal.

After that, the temperature of the substrate is raised and maintained at 1150 ° C., acetylene gas is introduced into the reaction chamber 10 through the nozzle 15, and at the same time, the electron beam generator 16 is activated to operate the crucible.
The Si substrate 1 is irradiated with the silicon in 17 in an atomic state. At this time, the molecular beam intensity measuring device (not shown) is monitored to monitor the molecular beam intensity (Ia) of acetylene and the molecular beam intensity (Ia) of silicon.
b), that is, the molecular beam intensity ratio (Ia / Ib) is 100 or less (third step). As a result, as shown in FIG.
The SiC single crystal buffer layer 4 is formed at a slow growth rate of 30 Å / min or less. This 3C-SiC single crystal buffer layer 4 is 3C-S
Since the surface of the iC carbonization buffer layer 2 is rough, the upper surface is formed smooth so that the thickness of the layer grown on the 3C-SiC single crystal buffer layer 4 becomes uniform. The smoothness of the 3C-SiC single crystal buffer layer 4 is detected by the electron beam diffraction apparatus.

After the 3C-SiC single crystal buffer layer 4 is formed so that its upper surface is smooth, the substrate temperature is further raised and maintained at 1200 ° C to set the molecular beam intensity ratio to 100 or less (fourth step). . As a result, the 3C-SiC single crystal 3 becomes 3 as shown in FIG.
It is formed at a growth rate of 100 Å / min or less, which is higher than that of the C-SiC single crystal buffer layer 4.

When the desired thickness of the 3C-SiC single crystal 3 is formed, the supply of acetylene gas and silicon into the reaction chamber 10 is stopped,
The reaction is completed.

FIG. 3 is a graph showing the substrate temperature in each step of the present invention described above, where the horizontal axis represents time and the vertical axis represents the substrate temperature (° C.).
Is shown.

As understood from this figure, in the case of the present invention, since the layer growth is performed in a high vacuum, the 3C-SiC carbonization buffer layer 2, the 3C-SiC single crystal buffer layer 4 and A 3C-SiC single crystal can be formed. Further, since the substrate temperature can be lowered, the manufactured semiconductor device has a small amount of impurities taken in from the reaction system and has no lattice defects such as slip lines.

In the above example, the silicon source was previously placed in the reaction chamber of the chemical vapor beam apparatus to perform layer growth, but the present invention does not need to use this apparatus. It can also be carried out by supplying a gas containing Si (for example, SiH ₄ , SiHC 1) and a hydrocarbon gas (for example, C ₃ H ₈ ) into the reaction chamber of the semiconductor manufacturing apparatus that can be held from the outside. In this case, the optimum growth temperature and the molecular beam intensity ratio differ depending on the type of the source.

Further, by heating the gas source at a certain high temperature, even if the gas source is cracked from a stable molecular state to an active molecular state and then supplied, a 3C-SiC single crystal layer can be generated, and the growth temperature is also increased. Naturally the temperature is lowered.

〔effect〕

As described above in detail, in the case of the present invention, since the layers are grown in a high vacuum, it is possible to grow each layer while keeping the substrate at a relatively low temperature. Therefore, the amount of impurities taken in from the reaction system to each layer can be increased. Can be reduced and the occurrence of lattice defects can be prevented. Furthermore, since a 3C-SiC single crystal buffer layer is formed,
The present invention has excellent effects such as smoothing the surface of a C-SiC single crystal.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a sectional structural view of a semiconductor device manufactured by the present invention, FIG. 3 is a graph showing a transition of substrate temperature in the case of the present invention, and FIG. FIG. 4 is a cross-sectional structure diagram of a conventional device. 1 ... Si substrate, 2 ... 3C-SiC carbonized buffer layer, 3 ... 3
C-SiC single crystal, 4 ... 3C-SiC single crystal buffer layer, 10 ...
… Reaction chamber

Claims (1)

[Claims] 1. A method of manufacturing a 3C-SiC semiconductor device comprising a 3C-SiC carbonization buffer layer between a Si substrate and a 3C-SiC single crystal, wherein a hydrocarbon gas and Si are contained in a reaction chamber kept at a high vacuum. Are reacted to form a 3C-SiC carbonization buffer layer on the Si substrate in the reaction chamber, and then the temperature of the Si substrate is raised to raise the temperature of 3C-Si on the Si substrate.
After forming the C single crystal buffer layer, the Si substrate temperature is further raised to form the 3C-SiC single crystal at a faster rate than when the 3C-SiC single crystal buffer layer is formed. Manufacturing method.