KR20130069252A - Method for deposition of silicon carbide and silicon carbide epi wafer - Google Patents

Abstract

PURPOSE: A silicon carbide deposition method and a silicon carbide epitaxial wafer are provided to change the surface of a silicon carbide wafer into a carbon-rich state by injecting a carbon source as an intermediate compound before deposition. CONSTITUTION: A wafer is prepared in a susceptor(ST10). A carbon source is injected into the susceptor(ST20). An intermediate compound is generated by injecting reaction gas including carbon and silicon into the susceptor(ST30). A silicon carbide epitaxial layer is formed on the wafer by reacting the intermediate compound and wafer(ST40). [Reference numerals] (ST10) Step of preparing a wafer; (ST20) Step of inserting a carbon source; (ST30) Step of generating a semi-product; (ST40) Step of reaction

Description

Silicon Carbide Deposition Method and Silicon Carbide Epi Wafer {METHOD FOR DEPOSITION OF SILICON CARBIDE AND SILICON CARBIDE EPI WAFER}

The present disclosure relates to a silicon carbide deposition method and a silicon carbide epi wafer.

In general, chemical vapor deposition (CVD) is widely used as a technique for forming various thin films on a substrate or a wafer. The chemical vapor deposition method is a deposition technique involving a chemical reaction, which uses a chemical reaction of a source material to form a semiconductor thin film, an insulating film, and the like on the wafer surface.

Such a chemical vapor deposition method and a vapor deposition apparatus have recently attracted attention as a very important technology among thin film forming techniques due to miniaturization of semiconductor devices and development of high efficiency and high output LED. It is currently used to deposit various thin films such as silicon films, oxide films, silicon nitride films or silicon oxynitride films, tungsten films and the like on a wafer.

For example, in order to deposit a silicon carbide thin film on a substrate or wafer, a reactive gas capable of reacting with the wafer must be introduced. Conventionally, as a raw material, silane (SiH ₄ ) and ethylene (C ₂ H ₄ ), which are standard precursors, or methyltrichlorosilane (MTS) are added thereto, and the raw material is heated to form CH ₃ , SiCl. After producing an intermediate compound such as _x , the intermediate compound was introduced into the deposition unit and reacted with a wafer located in the susceptor to deposit a silicon carbide epi layer.

However, on the surface of the wafer on which the silicon carbide epitaxial thin film layer is deposited, silicon has a very high degree of distribution rather than a state in which carbon and silicon are uniformly distributed. At this time, such silicon has a problem that can cause defects in the epi wafer because it increases the surface roughness on the wafer surface.

Accordingly, there is a need for a method capable of changing the surface of the silicon carbide wafer.

Example is a silicon carbide epitaxial wafer manufacturing method and silicon carbide to produce a silicon carbide epi wafer having a surface roughness of 1 nm or less by modifying the surface of the wafer to a carbon-rich (C-rich) surface when depositing silicon carbide on the wafer An epi wafer is provided.

Silicon carbide deposition method according to the embodiment comprises the steps of preparing a wafer in a susceptor; Injecting a carbon source into the susceptor; Injecting a reaction gas into the susceptor to generate an intermediate compound; And reacting the intermediate compound with the wafer to form a silicon carbide epitaxial layer on the wafer.

Silicon carbide epitaxial wafer according to the embodiment, the wafer; And a silicon carbide epitaxial layer formed on the wafer, wherein the surface roughness of the silicon carbide epitaxial layer is 1 nm or less.

The silicon carbide deposition method according to the embodiment may change the surface of the silicon carbide wafer into a carbon-rich carbon-rich (C-rich) state by introducing a carbon source before depositing an intermediate compound as a raw material on the silicon carbide wafer. Can be.

The silicon carbide epitaxial wafer on which the silicon carbide epitaxial layer is deposited on the silicon carbide wafer reduces surface roughness to 1 nm or less, and thus can produce a high quality silicon carbide epitaxial wafer.

1 is a process flowchart of a silicon carbide deposition method according to an embodiment.
2 is a diagram illustrating a process of injecting a carbon source onto a silicon carbide wafer.
3 is a view showing the surface state of a silicon carbide wafer in which the carbon source is injected.
4 is a diagram illustrating a process of depositing an epitaxial layer by adding a reaction gas onto the silicon carbide wafer.
5 illustrates a silicon carbide epitaxial wafer according to an embodiment.
6 is an exploded perspective view illustrating a decomposition of the deposition apparatus according to the embodiment.
7 is a perspective view illustrating a deposition apparatus according to an embodiment.
FIG. 8 is a cross-sectional view taken along line II ′ in FIG. 7.

In the description of embodiments, each layer, region, pattern, or structure may be “on” or “under” the substrate, each layer, region, pad, or pattern. Substrate formed in ”includes all formed directly or through another layer. The criteria for top / bottom or bottom / bottom of each layer are described with reference to the drawings.

The thickness or the size of each layer (film), region, pattern or structure in the drawings may be modified for clarity and convenience of explanation, and thus does not entirely reflect the actual size.

Hereinafter, a method of manufacturing a silicon carbide epitaxial wafer according to an embodiment will be described with reference to FIGS. 1 to 5.

1 is a view showing a process flow diagram of a silicon carbide deposition method according to an embodiment, Figure 2 is a view showing a process of injecting a carbon source on a silicon carbide wafer, Figure 3 is a view of the silicon carbide wafer 4 is a view illustrating a surface state, and FIG. 4 is a view illustrating a process of depositing an epi layer by adding a reaction gas onto the silicon carbide wafer, and FIG. 5 is a view showing a silicon carbide epi wafer according to an embodiment. .

Referring to FIG. 1, a silicon carbide deposition method according to an embodiment may include preparing a wafer (ST10); Injecting a carbon source (C source) into the susceptor (ST20); Injecting a reaction gas into the susceptor to generate an intermediate compound (ST30); And reacting the intermediate compound with the wafer to form a silicon carbide epitaxial layer on the wafer (ST40).

In preparing the wafer (ST10), the wafer may be positioned in a susceptor. In this case, the wafer may be a silicon carbide wafer.

Subsequently, in the step ST20 of injecting a carbon source into the susceptor, an alkane (C _n H _{2n +2} , where 1 ≦ _n ≦ 3) and an alkene (C _n H _{2n −2} , where ₂ ≦ _n ≦ 3) or a carbon compound containing alkyne (C _n H _2n , where ₂ ≦ _n ≦ 3). The carbon compound may be added after the susceptor is heated to a temperature of 1500 ℃ to 1575 ℃.

As shown in FIG. 2, the surface of the silicon carbide bulk wafer may be richer in silicon (Si) than in carbon (C). However, such silicon may form a constant protrusion on the surface of the wafer to roughen the surface of the silicon carbide wafer. Such surface roughness may cause defects to be generated on the silicon carbide wafer, and thus, when the silicon carbide epitaxial layer is deposited on the silicon carbide wafer, the defects may be extended to affect the silicon carbide epitaxial layer. Can be.

Accordingly, as shown in FIG. 3, in the silicon carbide deposition method according to the embodiment, carbon-rich carbon-rich (C-rich) is formed on the surface of the silicon carbide wafer by the step of introducing the carbon source to the surface of the silicon-rich silicon carbide wafer. -rich) state. That is, the susceptor may be heated to a temperature of 1500 ° C. to 1575 ° C., whereby carbon included in the carbon compound may form a carbon layer on the surface of the silicon carbide wafer. Accordingly, the silicon carbide wafer having a flat surface can be formed by removing the protrusion caused by the silicon.

Subsequently, in the step of generating an intermediate compound by adding a reaction gas to a susceptor (ST30) and the step of reacting the intermediate compound and the wafer to form a silicon carbide epitaxial layer on the wafer (ST40), the raw material, that is, the reaction A gas may be used to generate an intermediate compound that reacts with the wafer or substrate in the susceptor, and the intermediate compound may be injected into the susceptor to react with the wafer to form a silicon carbide epitaxial layer on the wafer. have.

Hereinafter, the silicon carbide epitaxial layer is formed by reacting the intermediate compound with the wafer with reference to FIGS. 5 to 7.

5 to 7, a deposition apparatus according to an embodiment includes a chamber 10, a susceptor 20, a source gas line 40, a wafer holder 30, and an induction coil 50.

The chamber 10 may have a cylindrical tube shape. Alternatively, the chamber 10 may have a rectangular box shape. The chamber 10 may accommodate the susceptor 20, the source gas line 40, and the wafer holder 30.

In addition, both ends of the chamber 10 are hermetically sealed, and the chamber 10 may prevent inflow of external gas and maintain a degree of vacuum. The chamber 10 may include quartz having high mechanical strength and excellent chemical durability. In addition, the chamber 10 has improved heat resistance.

In addition, the heat insulating part 60 may be further provided in the chamber 10. The heat insulating part 60 may perform a function of preserving heat in the chamber 10. Examples of the material used as the heat insulating part include nitride ceramics, carbide ceramics or graphite.

The susceptor 20 is disposed in the chamber 10. The susceptor 20 receives the source gas line 40 and the wafer holder 30. In addition, the susceptor 20 accommodates a substrate such as the wafer (W). In addition, the reaction gas is introduced into the susceptor 20 through the source gas line 40.

As shown in FIG. 3, the susceptor 20 may include a susceptor upper plate 21, a susceptor lower plate 22, and susceptor side plates 23. In addition, the susceptor upper plate 21 and the susceptor lower plate 22 face each other.

The susceptor 20 may be manufactured by placing the susceptor upper plate 21 and the susceptor lower plate 22 and attaching the susceptor side plates 23 to both sides thereof.

However, since the embodiment is not limited thereto, a space for the gas passage may be made in the susceptor 20 of the rectangular parallelepiped.

The susceptor 20 may include graphite having high heat resistance and easy processing to withstand conditions such as high temperature. In addition, the susceptor 20 may have a structure in which silicon carbide is coated on the graphite body. In addition, the susceptor 20 may be induction heated by itself.

The reaction gas supplied to the susceptor 20 may be decomposed into an intermediate compound by heat, and in this state, may be deposited on the wafer W or the like. For example, the reaction gas is methyltrichlorosilane (MTS), which is a liquid raw material, silane (SiH ₄ ) and ethylene (C ₂ H ₄ ), which are gaseous raw materials, or silane and propane (C ₃ H ₈ ). can do. However, embodiments are not limited thereto, and the reaction gas may include various compounds including carbon and silicon.

The raw material is decomposed into radicals containing silicon or carbon, and a silicon carbide epitaxial layer may be grown on the wafer (W). More specifically, the radical may be CH _x · (1 ≦ _x <4) or SiCl _x · (1 ≦ _x <4) including CH ₃ , SiCl, SiCl ₂ , SiHCl ₂ , SiHCl ₂ , etc. have.

The source gas line 40 may have a square tube shape. Examples of the material used for the source gas line 40 include quartz and the like.

The wafer holder 30 is disposed in the susceptor 20. In more detail, the wafer holder 30 may be disposed at the rear of the susceptor 20 based on the direction in which the source gas flows. The wafer holder 30 supports the wafer (W). Examples of the material used for the wafer holder 30 include silicon carbide or graphite.

The induction coil 50 is disposed outside the chamber 10. In more detail, the induction coil 50 may surround the outer circumferential surface of the chamber 10. The induction coil 50 may induce heat generation of the susceptor 20 through electromagnetic induction. The induction coil 50 may wind an outer circumferential surface of the chamber 10.

The susceptor 20 may be heated to a temperature of about 1500 ° C. to about 1700 ° C. by the induction coil 50. As described above, in the section where the temperature rises to a temperature of 1500 ° C. to 1575 ° C., the surface of the wafer may be changed to a carbon-rich state by adding the carbon source. Thereafter, at a temperature of 1575 ° C. to 1700 ° C., the source gas is decomposed into intermediate compounds, introduced into the susceptor, and injected into the wafer (W). By the radicals injected onto the wafer W, a silicon carbide epitaxial layer is formed on the wafer W.

As such, the silicon carbide epitaxial growth apparatus according to the embodiment forms a thin film such as the epi layer on a substrate such as the wafer W, and the remaining gas is disposed at an end of the susceptor 20. Through, it can be discharged to the outside.

Referring to FIG. 5, a silicon carbide epitaxial wafer manufactured by the silicon carbide deposition method is shown. The silicon carbide epitaxial wafer deposits a silicon carbide layer after changing the surface on the wafer to a carbon-rich carbon-rich state in a silicon-rich environment, thereby eliminating a surface defect and having a surface roughness of 1 nm or less. It can manufacture. Preferably, the surface roughness may be 0.1 nm to 1 nm. That is, since a carbon layer serving as a buffer layer is deposited between the silicon carbide wafer and the silicon carbide epitaxial layer, and a silicon carbide epitaxial layer is deposited between the carbon layers, surface roughness can be reduced, thereby producing a high quality silicon carbide epitaxial wafer. can do.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

Claims (11)

Preparing a wafer in a susceptor;
Injecting a carbon source into the susceptor;
Injecting a reaction gas into the susceptor to generate an intermediate compound; And
Reacting the intermediate compound with the wafer to form a silicon carbide epitaxial layer on the wafer. The method of claim 1,
The carbon source may be an alkane (C _n H _{2n +2} , where 1 ≦ _n ≦ 3), an alkene (C _n H _{2n −2} , where ₂ ≦ _n ≦ 3) or an alkyne (C _n H _2n , where ₂ ≦ _n ≦ 3 Silicon carbide deposition method comprising a carbon compound). The method of claim 1,
And the reaction gas comprises carbon (C) and silicon (Si). The method of claim 1,
Wherein said intermediate compound comprises CH _x. (1≤x <4) or SiCl _x. (1≤x <4). The method of claim 1,
The carbon source is a silicon carbide deposition method that is introduced at a temperature of 1500 ℃ to 1575 ℃. The method of claim 1,
The carbon source is a silicon carbide deposition method that is introduced at a temperature of 1500 ℃ to 1545 ℃. The method according to claim 5 or 6,
Wherein the carbon source is 1 to 10 minutes silicon carbide deposition method. The method of claim 1,
The reaction gas is a silicon carbide deposition method for producing an intermediate compound at a temperature of 1550 ℃ to 1700 ℃. The method of claim 1,
And the wafer comprises a silicon carbide wafer. wafer;
A silicon carbide epitaxial layer formed on the wafer,
The silicon carbide epitaxial wafer has a surface roughness of 1 nm or less. The method of claim 10,
A silicon carbide epitaxial wafer comprising a carbon buffer layer between the wafer and the silicon carbide epitaxial layer.

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