JPH02170542A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to form selectively an epitaxial silicon layer by a method wherein an impurity is diffused in a single crystal silicon substrate and an insulating substance layer on the surface of an element is removed to expose a single crystal silicon epitaxial layer which is the layer under the surface. CONSTITUTION:Silicon layers 4 and 5 are formed and the introduction of an impurity, such as As, P, B and the like, is performed. Subsequently, the poly silicon layer only is all oxidized 9 by a difference between the poly silicon layer 4 and the epitaxial silicon layer 5 in the oxidizing rate. At that time, the impurity is diffused from the epitaxial silicon layer 5 into an Si substrate to form impurity diffused layers 10. After that, the unnecessary part of an oxide layer is removed by etching. Thereby, the formation of a selective epitaxial silicon layer, by which the epitaxial silicon layer is grown on the single crystal silicon layer exposed on the surface of an element, becomes possible.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device having a selectively epitaxially grown film on a semiconductor substrate, a semiconductor having selectively epitaxially grown silicon only on a single silicon exposed on the substrate surface by a method of growing silicon at a low temperature. The purpose is to provide a method for manufacturing a device, (a) performing CVD growth on a semiconductor single crystal silicon substrate having an insulating film on a part of the surface, epitaxially growing single crystal silicon on the single crystal silicon substrate, and at the same time growing polycrystalline silicon on the insulating film;
(b) After introducing impurities into the single-crystal silicon epitaxial layer and the polycrystalline silicon on the insulating film, (c) performing an oxidation treatment so that the entire thickness of the polycrystalline silicon becomes an insulating material, and the single-crystal silicon epitaxial layer becomes an insulating material. Making only the surface portion an insulating material, and diffusing the impurity from the single crystal silicon epitaxial layer into the single crystal silicon substrate; (d) removing the surface insulating material to expose the underlying single crystal silicon epitaxial layer; Configure it to do so.

[Industrial Field of Application] The present invention relates to a method for manufacturing a semiconductor device. More specifically, the present invention relates to a method of manufacturing a semiconductor device having a selectively epitaxially grown film on a semiconductor substrate. In the manufacturing process of semiconductor devices, it is often necessary to perform selective epi-silicon formation in which epitaxial silicon is grown only on single silicon (single-crystal St) exposed on the surface of the device.The present invention relates to improvements in the formation method.

[Conventional technology] Conventional techniques for forming epitaxial silicon on a silicon substrate include (1) epitaxial silicon is grown on the entire surface of the substrate, and then selectively oxidized using a mask to oxidize only the desired areas; There are two methods: (2) selective episilicon growth using a CVD method in which single silicon is grown only on a single crystal base;

[Problems to be Solved by the Invention] Although the method (1) above is used for manufacturing bipolar devices, it is not often used for manufacturing MOS devices, and the devices that can be manufactured are limited. On the other hand, since method (2) above is generally a high-temperature growth method of 950 to 1000°C, many defects enter the substrate single crystal, and the threshold when applying method (2) to the fabrication of MoS transistor elements. A problem arises in that it is difficult to control the voltage (Vth).

That is, since the selective epi-silicon growth method is a high-temperature growth method, impurities in the channel portion of the MOS transistor diffuse to the outside, causing fluctuations in the threshold voltage.

The present invention can be applied only on a single silicon layer exposed on the substrate surface by a method of growing silicon at low temperatures! An object of the present invention is to provide a method for manufacturing a semiconductor device having I-treated epitaxial silicon.

[Means for Solving the Problems] The present invention provides (a) performing CVD growth on a semiconductor single-crystal silicon substrate having an insulating film on a portion of the surface, epitaxially growing single-crystal silicon on the single-crystal silicon substrate,
At the same time, polycrystalline silicon is grown on the insulating film, (b) impurities are introduced into the monocrystalline silicon epitaxial layer and the polycrystalline silicon on the insulating film, and (c) an oxidation treatment is performed to reduce the thickness of the polycrystalline silicon. The whole is made of insulating material,
The single-crystal silicon epitaxial layer uses an insulating material only on its surface, and the impurities are diffused from the single-crystal silicon epitaxial layer into the single-crystal silicon substrate, and (d) the insulating material on the surface is removed and the underlying layer is made of an insulating material. This is a method of manufacturing a semiconductor device characterized by comprising steps (a) to (d) of exposing a crystalline silicon epitaxial layer.

Hereinafter, the configuration of the present invention will be explained in detail.

In the first step (a) of the present invention, episilicon and polysilicon are grown simultaneously. This growth can be carried out at a low temperature below 900°C, especially below 800"C. This significantly reduces the number of defects entering the silicon substrate.
In the next step (b), impurities are introduced into the silicon and polycrystalline silicon on the insulating film. In the subsequent step (c), the difference in oxidation rate between polysilicon and episilicon is utilized to oxidize the entire thickness of the former, while leaving only a portion of the episilicon thickness necessary for device formation in the latter. .

The remaining episilicon film is used as a selective episilicon film. Impurities are diffused into the silicon substrate under high temperatures during the oxidation process, creating necessary regions such as sources and drains. In this diffusion method, impurities are diffused into the silicon substrate through epi-silicon rather than directly into the silicon substrate, creating a concentration gradient of impurities from the epi-silicon to the silicon substrate surface, resulting in an impurity concentration gradient within the silicon substrate. By making the diffusion layer shallower, shallow junk can be achieved.

In the next step (d), unnecessary portions of the insulating material are removed, and then known steps such as electrode formation and glabellar insulation are performed.

In a preferred embodiment of the invention, the remaining episilicon allows for planarization. That is, by reducing the level difference between the remaining epitaxial silicon and the surrounding area, the electrodes, wiring patterns, or glabellar insulating film deposited thereon will be flattened. As a result, the short channel MO
Even when manufacturing SLSIs, there is no need to create electrode contact windows with a large aspect ratio (ratio of diameter to depth), and a large margin for positioning can be obtained, making it easier to form electrode wiring patterns.

[Works] Although the method of the present invention, which simultaneously grows copolysilicon and episilicon, does not have growth selectivity, it enables low-temperature growth, which reduces defects entering the silicon substrate and suppresses impurity diffusion in the channel. . (Poly)silicon, which does not grow in unnecessary areas due to lack of growth selectivity, is oxidized throughout its entire thickness and then removed, since the oxidation rate is faster with single silicon after impurity introduction. This oxidation treatment also serves as a diffusion treatment for impurities in episilicon, and is simply an additional process for removing unnecessary parts, which does not increase the number of processes, but is an important process for forming shallow sources and drains. ing. Hereinafter, embodiments will be described with reference to the drawings.

(Example) In FIG. 1, 1 is a Si substrate, 2 is a field oxide film, 6 is a gate insulating film, 7 is a polysilicon electrode, and 8 is an At
) wiring, all of which are well known in MOSLSI.

For example, disilane (
3s e cm) +Hz mixed gas, 800℃, 60t
It was carried out for 6 minutes under the conditions of orr, and 2000 silicone (
4,5).

Silicon 4 is polysilicon 4 on field oxide film 2.
Therefore, on the Si substrate 1, episilicon 5 is formed.

Next, as shown in FIG. 2, impurities such as As, P, and B are introduced. The conditions for introducing impurities are, for example, As or P as an N-type impurity at an acceleration energy of 70 keV and a dose of 4X10"/cm". The impurity concentration of the epitaxial silicon layer 5 after impurity introduction is 5x101@~10''cm.
-' is preferable. Next, as shown in FIG. 3, due to the difference in oxidation rate between polysilicon 4 and episilicon 5, only polysilicon is completely oxidized (9). At that time, impurities are removed from episilicon 5. Diffused into the Si substrate to form an impurity diffusion layer 10 In the figure, 9 collectively indicates an oxide layer in which the entire polysilicon 4 is oxidized and an oxide layer in which only the surface of the episilicon 5 is oxidized. 9' is an oxide layer formed by oxidizing the side surface of the silicon gate 7. Oxidation is performed, for example, at 900° C. in a wet atmosphere, and the oxidation rate ratio at this time is polysilicon/episilicon=1.
3 to 1.5. The thickness of the oxidized f&remaining episilicon 5 is, for example, 800 mm.

Thereafter, as shown in FIG. 4, unnecessary portions of the oxide layer are removed by etching.

FIG. 5 shows a completed drawing. Reference numeral 11 indicates an insulating film between the eyebrows, and 12 a cover film, both of which are known.

FIG. 6 shows an oxidation process similar to that in FIG. 3. In FIG.
．． The thickness is left almost the same as 8. For this name, CV
In step D, it is necessary to deposit a thick silicon layer. If the oxide film is removed following the step shown in FIG. 6, a substantially flat surface can be obtained over the entire surface.

[Effects of the Invention] As described above, according to the present invention, episilicon with fewer defects in the substrate silicon can be obtained, and leakage current to the substrate can be reduced. Furthermore, an impurity diffusion layer can be formed at the same time during the oxidation process, and shallow junctions can be measured.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the Si growth process, Figure 2 is a diagram showing the ion implantation process, Figure 3 is a diagram showing the oxidation process, Figure 4 is a diagram showing the oxide film removal process, and Figure 5 is a completed diagram. , FIG. 6 shows an embodiment for achieving flattening, and is a diagram corresponding to FIG. 3. 1-Si substrate, 2-Field oxide film, polysilicon, 5-Episilicon, 6-Gate insulating film, 7-Polysilicon electrode, 9-Oxide layer] Molecular removal? Figure 4 Si8 to long workpiece Figure 1 ion, main process helmet bottom Figure 5 flat! Column A, Figure 6, Procedural Amendment Form 6, Drawing subject to amendment 7゜Contents of amendment 1, Indication of the case As shown in the appendix No. 326682 of 1988 2, Invention of the invention Name semiconductor device! Manufacturing method 8, List of attached documents 3, Person making the amendment Figure 1 to Figure 6 1 Relationship to the case

Claims (1)

[Claims] 1. (a) Perform CVD growth on a semiconductor single crystal silicon substrate having an insulating film on a part of the surface, epitaxially grow single crystal silicon on the single crystal silicon substrate, and simultaneously grow polycrystalline silicon on the insulating film. (b) After introducing impurities into the single crystal silicon epitaxial layer and the polycrystalline silicon on the insulating film, (c) performing an oxidation treatment,
The entire thickness of polycrystalline silicon is an insulating material, and the single-crystal silicon epitaxial layer only has an insulating material on its surface, and the impurity is diffused from the single-crystal silicon epitaxial layer into the single-crystal silicon substrate.
d) A method for manufacturing a semiconductor device, comprising steps (a) to (d) of removing an insulating material on the surface to expose an underlying single-crystal silicon epitaxial layer.