JPH0456798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of processing a silicon substrate.

[Conventional technology]

Traditionally, silicon (Si) substrate processing methods have used photolithography, plasma, reactive ions, etc., as described in VLSI Process Data Handbook (Science Forum, 1981), pages 380 to 492. Dry etching was common.

[Problem that the invention seeks to solve]

However, the conventional method has had problems such as contamination and damage to the substrate surface due to etching gas.

An object of the present invention is to provide a method for processing a silicon substrate that does not cause contamination or damage to the substrate surface by using Si molecular beam epitaxial growth (MBE) instead of the conventional substrate processing technology using etching. .

[Means for solving problems]

The silicon substrate processing method of the present invention involves forming a SiO ₂ film on the surface of the silicon substrate, forming grooves in the SiO ₂ film, and increasing the substrate temperature at which the SiO ₂ film is etched and epitaxial growth occurs on the silicon substrate surface. and irradiation conditions, the Si molecular beam is at least
It is characterized by irradiation until the SiO ₂ film is completely removed.

[Effect]

The principle by which the present invention provides a method for processing a silicon substrate that causes less contamination and damage to the substrate surface than in the prior art will be explained below.

When a SiO ₂ film formed on a Si substrate is irradiated with a Si molecular beam, amorphous or polycrystalline silicon is usually deposited on the SiO ₂ film. However, if the temperature of the substrate is kept above a certain temperature at this time, the SiO ₂ film will be etched. For example, Japanese Journal of Applied Physics (Jpn.J.
Appl.Phys.) Volume 21, 1982, page 534, the density of Si molecules reaching the substrate surface is
In the case of 1.1×10 ¹⁶ cm ^-2 sec ^-1 , the etching phenomenon of the SiO ₂ film occurs when the substrate temperature is 1000°C or higher. At this time (substrate temperature 1000℃) the etching rate is approximately 35Å/
sec, and under these conditions the speed is 20 on the Si clean surface.
MBE growth of Å/sec occurs.

Therefore, if a SiO ₂ part and an exposed Si part are provided on the Si substrate and MBE growth is performed under the above conditions, the SiO ₂ will be etched and the exposed Si part will grow epitaxially, and the SiO ₂
After completely removing SiO 2 , a Si substrate is obtained which is processed into a pattern opposite to that of the original SiO ₂ . Also, if you first prepare thick and thin parts of SiO ₂ ,
After uniform etching of SiO ₂ occurs at first,
Etching and epitaxial growth occur simultaneously as described above, and the Si substrate can still be processed.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the processing steps of the first embodiment of the present invention. First, a thick SiO ₂ film 20 is deposited on the surface of a silicon (100) substrate 10 by thermal oxidation.
After forming the SiO ₂ film 20 with a thickness of 2 μm, stripe-shaped grooves 30 with a width and depth of 2 μm are dug in the SiO 2 film 20 using conventional photolithography and reactive ion etching techniques to expose the Si substrate 10, as shown in FIG. 1a. The following state is obtained.

Next, this substrate was introduced into an MBE device, and after obtaining a clean surface on the Si exposed part using the argon sputtering method, Si molecular beams were applied to the substrate at a density of 1.1× at a substrate temperature of 1000°C.
Irradiation was performed at 10 ¹⁶ cm ^-2 sec ^-1 . Then, etching of the SiO ₂ film 20 and MBE growth on the exposed Si portion occur simultaneously, and as shown in FIG. 2b, the thickness of the SiO ₂ film 20 decreases, and a silicon epitaxial growth layer 40 is formed on the exposed Si portion. It will be done. After this state, approximately
After 10 minutes, the SiO ₂ film 20 was completely removed by etching and processed into the shape shown in Figure 1c.
A Si substrate is obtained.

Further, when MBE growth is continued from the state shown in Figure 1c, the substrate surface becomes a silicon epitaxial growth layer 4.
A Si substrate processed into a similar shape covered only with zero is obtained.

FIG. 2 is a sectional view showing the processing steps of a second embodiment of the present invention. First, a thick SiO ₂ film 60 is deposited on the surface of a silicon (100) substrate 50 by thermal oxidation.
After forming 2.2 μm, a striped groove 70 with a width and depth of 2 μm is dug using ordinary photolithography and reactive ion etching without exposing the Si substrate 50, resulting in the state shown in Figure 2a. It will be done.

Next, this substrate was introduced into an MBE apparatus, and the substrate was irradiated with a Si molecular beam at a substrate temperature of 1000° C. at a density of 1.1×10 ¹⁶ cm ⁻² sec ⁻¹ as in the first example. Then, the SiO ₂ film 60 is etched, and after about 2.5 minutes, the part covered with the SiO 2 film 60 and the part covered with the SiO ₂ film 60 are etched as shown in FIG. 2b.
A portion where Si is exposed is obtained, and the same state as 1a described in the first embodiment is obtained.

Thereafter, under the same conditions as described in the first embodiment, etching of the remaining SiO ₂ film 60 and MBE growth on the exposed Si portion are performed simultaneously, the SiO ₂ film 60 is removed by etching, and the silicon epitaxy is A silicon substrate is obtained which is formed with a hollow growth layer 80 and processed into the shape shown in FIG. 2c.

Furthermore, if MBE growth is continued from the state shown in FIG. 2c in the same manner as in the first embodiment, a Si substrate processed into the same shape with the substrate surface covered only with the silicon epitaxial growth layer 80 is obtained.

In the above two embodiments, examples using silicon (100) substrates were shown, but similar processing can be performed using substrates with other orientations. Further, the substrate temperature, the density of Si molecules reaching the substrate, etc. are not limited to the above embodiments. Further, the shape of the SiO ₂ film processed is not limited to a stripe shape, and Si substrates processed into various shapes can be obtained by processing the SiO 2 film into other shapes.

〔Effect of the invention〕

As explained above, according to the present invention, since MBE growth is utilized, a method for processing a silicon substrate can be obtained that does not cause contamination or damage to the substrate surface, compared to the conventional silicon substrate processing technology using etching. It is also possible to dope impurities during MBE growth, and it is possible to obtain a silicon substrate having Si convex portions with controlled shapes and impurity concentrations.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the processing steps of a first embodiment of the present invention, and FIG. 2 is a sectional view showing the processing steps of the second embodiment of the invention. 10,50...Silicon substrate, 20,60...
SiO ₂ film, 30, 70... groove, 40, 80... silicon epitaxial growth layer.

Claims (1)

[Claims] 1. A SiO ₂ film is formed on the surface of a silicon substrate, and this
A groove is formed in the SiO ₂ film, and the Si molecular beam is irradiated at least until the SiO ₂ film is completely removed at a substrate temperature and irradiation conditions that will cause the SiO ₂ film to be etched and epitaxial growth to occur on the silicon substrate surface. Characteristic silicon substrate processing method. 2. In the method of processing a silicon substrate according to claim 1, the groove is formed so that the surface of the silicon substrate is exposed, and etching and epitaxial growth of the SiO ₂ film are simultaneously progressed by the Si molecular beam irradiation. A method for processing a silicon substrate, characterized by: 3. In the method of processing a silicon substrate according to claim 1, the groove is formed without exposing the silicon substrate surface, and the silicon substrate surface is exposed at the bottom of the groove by the Si molecular beam irradiation. 1. A method of processing a silicon substrate, characterized in that after etching the SiO ₂ film up to a maximum of 100 nm, etching and epitaxial growth of the SiO ₂ film proceed simultaneously.