JP2848158B2 - Method for manufacturing semiconductor silicon epitaxial substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an edgeless
Method for manufacturing semiconductor silicon epitaxial substrate
I do. More specifically, a thick silicon epitaxial layer having a thickness of, for example, 30 μm or more without an edge crown is formed.
The present invention relates to a method for manufacturing a semiconductor silicon epitaxial substrate having the same .

[0002]

2. Description of the Related Art IGBT (Insulated Gate)
In the growth of a thick-film epitaxial layer such as an epitaxial silicon substrate for manufacturing e Bipolar Transistor, a bulge called an edge crown 4 occurs on the outer peripheral portion of the silicon single crystal substrate 2 as shown in FIG. The edge crown 4 occurs only on the epitaxial layer growth side in the growth of the silicon epitaxial layer 3 using the cylinder type epitaxial device, but in the epitaxial layer growth using the pancake type epitaxial device (bell jar type device), It occurs on both the growth side (front side) and the back side of the substrate. The heights H ₁ and H ₂ of the edge crown depend on the thickness of the epitaxial layer to be grown, but may reach as large as 30 μm when the epitaxial layer is grown to about 100 μm. If the height of the edge crown exceeds 5 μm or 10 μm, the degree of adhesion between the mask and the epitaxial layer 3 at the time of forming the photolithographic pattern becomes poor, and there is a problem that the pattern forming accuracy is deteriorated.

Conventionally, when a precise photolitho pattern is required, when the edge uraun height exceeds 5 μm, the epitaxial layer growth apparatus, the chamfered shape of the substrate, the pocket shape of the susceptor for holding the substrate, and the growth temperature conditions are changed. Efforts are made to keep the edge crown height below the specified value by proper selection.

[0004]

However, in recent years, in a semiconductor silicon epitaxial substrate, a substrate having an increasingly thick epitaxial layer has been required. Therefore, the above-described epitaxial layer growth apparatus, substrate chamfered shape, substrate holding shape, etc. By appropriately selecting the pocket shape of the susceptor and the growth temperature conditions, it is difficult to keep the edge crown height below the standard value.

[0005] To cope with this, it is possible to reshape the edge crown with a chamfering machine before the device process, or to cut off only the edge crown with a surface grinder. However, both methods have the drawback of damaging the epitaxial surface, and the new problem that particles generated by the chamfering machine and surface grinding machine adhere to the epitaxial surface and become contaminated, and cannot be easily removed even by cleaning. Will occur.

Accordingly, an object of the present invention is to provide a thick silicon epitaxial substrate capable of removing an edge crown without damaging the epitaxial surface and contaminating the epitaxial substrate after the epitaxial layer is grown. It is to provide a manufacturing method.

[0007]

Means for Solving the Problems] semiconductor silicon epitaxial substrate manufacturing method of the present invention, the semi having a chamfered portion
Silicon epitaxial on conductor single crystal silicon substrate
Growing a layer and overlying the silicon epitaxial layer
Form a silicon oxide or nitride film as a protective film
And the step of reshaping the chamfer,
Etching the chamfered portion and removing the protective film
And (c) are performed in this order.

In the present invention, after the epitaxial layer is grown, a protective film is formed on the epitaxial layer, and then the chamfering machine (#
The edge crown generated by the epitaxial layer growth is removed by shaping the chamfered shape using about 600 to # 2000). As the protective film, an oxide film (eg, silicon oxide) or a nitride film (eg, silicon nitride) formed by a CVD method, or an oxide film formed by thermal oxidation of an epitaxial substrate is preferably used. The protective film thickness is 500 nm or more, preferably,
The thickness is set to 1000 nm or more.

Since the chamfered portion after the edge crown is removed is a rough surface, it may be a source of particles. If this poses a problem in the device process, the substrate from which the edge crown has been removed is immersed in a nitric acid-rich hydrofluoric or nitric acid solution or an alkaline solution and etched to smooth the chamfered portion. In addition, processing distortion remains in the chamfered portion, and dislocation may occur depending on a device process, which may be a serious problem. In this case, the etching margin is increased to completely remove the work distortion layer in the chamfered portion. After the removal of the edge crown (after etching when performing etching), the protective film on both surfaces of the substrate or one surface (on the epitaxial surface) is removed as necessary. If the protective film is an oxide film, use an aqueous solution of hydrofluoric acid to remove it. If the protective film is a nitride film, remove it by 160 ° C.
Use hot phosphoric acid at ~ 180 ° C.

[0010]

According to the present invention, the substrate is formed on a substrate having a chamfer.
To form a protective film on the epitaxial layer
Then, using a chamfering machine to reshape the chamfered part,
There is no damage to the epitaxial surface during shaping.
No particles adhere to the taxi surface
It is not contaminated by the slurry used for the picker.
As well as etch the reshaped chamfer
Sometimes the silicon epitaxial layer is protected by a protective film
Is done. In addition, rough and residual surfaces remaining in the chamfer after reshaping
Engineering distortion (generated during reshaping) is removed in the above etching process.
Is removed, so the reshaped part is the particle source
It is not a source of dislocations in the device process.
Never even. In addition, chamfering is performed by using an oxide film or a nitride film formed by CVD or an oxide film formed by thermal oxidation of an epitaxial substrate as the protective film, and setting the thickness to 500 nm or more, preferably 1000 μm or more. When it is applied to a machine, it becomes a sufficiently strong protective film. In addition, the chamfered part (surface
Remove and reshape part in nitric acid-rich hydrofluoric acid solution or
When etching in a re-solution , the latter is overwhelmingly faster in etching the silicon oxide film and silicon, so the silicon oxide film acts as a protective film, and only the chamfer reshaping part where silicon is exposed is etched. Receive. Sa
Furthermore, on a semiconductor single crystal silicon substrate having a chamfer
Since a silicon epitaxial layer is grown,
Substrate holding during epitaxial layer formation
Board does not stick to the susceptor for
There is no cracking problem.

[0011]

Next, an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. Example A silicon substrate was processed in the following order to prepare a semiconductor silicon epitaxial substrate. (1) P-type CZ single-crystal silicon, orientation <100>, diameter 125.4 mm, initial thickness 450 μm, silicon substrate 2 having a 1000 nm thick silicon oxide film 1 formed on the back surface of the substrate by CVD [FIG. )] Was set in a pancake-type epitaxial apparatus, and a thickness of 12
A 0 μm low-phosphorus-doped silicon epitaxial layer 3 was grown [FIG. 1 (b)]. The initial chamfer angle of the substrate at this time was 11 ° as shown in FIG.
When the height of the edge crown 4 (FIG. 1 (b)) was measured by a contact-type level difference measuring instrument, the maximum value was 10 μm on the epitaxial surface side (substrate front side), and the maximum value was 30 μm on the silicon substrate side (substrate back side). Met. (2) CVD oxide film growth machine (normal pressure, 450 ° C., SiH ₄
+ O ₂ ), a silicon oxide film 5 was grown as a protective film on the epitaxial layer 3 to a thickness of 1000 nm [FIG.
(C)]. (3) The silicon substrate 2 is chamfered by a chamfering machine 11 to have a substrate diameter of 125.0 mm and a chamfer angle of 11
°, chamfering number # 1500 [FIG. 1 (d),
(E)]. This chamfering reshaping slightly reduces the substrate diameter. In FIG. 1D, reference numeral 11a denotes a grindstone portion. (4) After the chamfered silicon substrate 2 was washed, it was immersed in a 61% nitric acid: 50% hydrofluoric acid = 30: 1 solution at room temperature to etch the chamfered reshaped portion 6 (Si exposed surface). The immersion time was as follows: P-type CZ single crystal silicon without protective film, orientation <100
>, The time for etching one side of the layer was 10 μm [FIG. 1 (f)]. (5) After removing the silicon oxide films 1 and 5 by immersing the silicon substrate 2 in an aqueous solution of hydrofluoric acid, the substrate is washed and dried to obtain a semiconductor silicon epitaxial substrate 7 [FIG.
(G)].

When the presence or absence of a flaw on the upper surface of the epitaxial layer 3 was measured for the substrate 7, no flaw was recognized. The attached particles were equivalent to those immediately after the epitaxial growth. Further, 25 substrates 7 were put in a storage box containing 25 substrates, and 1 hour of vibration and 1 hour of standing were repeated three times, and then the adhered particles were measured. Was equivalent to

[0013]

As is apparent from the above description, the present invention
In such a method of manufacturing a semiconductor silicon epitaxial substrate,
Is on a semiconductor single crystal silicon substrate having a chamfer,
Growing a silicon epitaxial layer;
Silicon oxide or nitride on the epitaxial layer
Forming the film as a protective film and realigning the chamfer
The process of shaping and the process of etching the reshaped chamfer
And the step of removing the protective film in this order
Therefore, a silicon epitaxial substrate having a thick silicon epitaxial layer having a thickness of 30 μm or more without edge crown can be manufactured. Moreover, it is possible to obtain a substrate having no scratch on the epitaxial surface and substantially no influence of contamination. Furthermore, the chamfer after reshaping
Is not a source of particles and dislocations
The effect of not being a source is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a silicon substrate showing a manufacturing process of a semiconductor silicon epitaxial substrate according to an embodiment of the present invention .
Is an explanatory view showing, (a) shows the formation of the silicon oxide film on the back surface (silicon) substrate, a (b) the substrate after the silicon epitaxial layer growth, the substrate after the (c) the protective film growth, (D) shows the substrate after chamfering and reshaping, (e) shows the substrate after chamfering and reshaping , (f) shows the substrate after etching,
(G) shows a semiconductor silicon epitaxial substrate.

FIG. 2 is a cross-sectional view of a main part for describing an edge crown generated in an outer peripheral portion of a silicon single crystal substrate.

[Description of Signs] 1 silicon oxide film 2 silicon substrate 3 epitaxial layer 4 edge crown 5 silicon oxide film (protective film) 6 chamfering reshaping section 7 semiconductor silicon epitaxial substrate 11 chamfering machine 11a grinding wheel section

Claims (8)

(57) [Claims] 1. A semiconductor single crystal silicon having a chamfer.
Step of growing a silicon epitaxial layer on a substrate
And a silicon oxide film on the silicon epitaxial layer
Or a step of forming a nitride film as a protective film,
Either reshaping the chamfered part and reshaping the chamfered part.
And a step of removing the protective film.
A method of manufacturing a semiconductor silicon epitaxial substrate, which is performed in order . 2. The thickness of said silicon epitaxial layer is
The method for producing a semiconductor silicon epitaxial substrate according to claim 1, wherein the thickness is 30 µm or more . 3. The protection film is formed by a CVD method.
The semiconductor according to claim 1 or 2, wherein
Of manufacturing a silicon epitaxial substrate. 4. The protective film has a thickness of 500 nm or more.
4. The method according to claim 1, wherein:
Method of manufacturing semiconductor silicon epitaxial substrate
Law. 5. The step of reshaping the chamfered portion includes the step of chamfering.
5. The method according to claim 1, wherein the step is carried out by using a refining machine.
A semiconductor silicon epitaxial substrate according to any one of claims 1 to 4.
Plate manufacturing method. 6. The step of reshaping the chamfered part,
The feature is to remove the edge crown generated in the chamfer
The semiconductor according to any one of claims 1 to 5,
A method for manufacturing a silicon epitaxial substrate. 7. Etching the reshaped chamfer.
Is performed in a nitric acid-rich hydrofluoric acid solution or an alkaline solution,
Line by immersing semiconductor silicon epitaxial substrate
The method according to any one of claims 1 to 6, wherein
The method for producing a semiconductor silicon epitaxial substrate according to the above. 8. The step of removing the protective film, wherein the protective film is
In the case of an oxide film, use an aqueous solution of hydrofluoric acid.
Claims characterized by using hot phosphoric acid
Item 8. A semiconductor silicon epitaxy according to any one of Items 7 to 9
Manufacturing method of metal substrate.