JPS6014471A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an effective junction of low resistance having shallow junction depth by a method wherein a semiburied type gate electrode is formed. CONSTITUTION:A field oxide film 22 is selectively formed on the surface part of a silicon substrate 21 by performing an LOCOS process. Then, a groove 23 is formed in the prescribed depth at the specified point of the part where the surface of the substrate 21 is exposed by performing photolithographic and etching processes, a gate oxide film 24 is formed on the inside coating of the groove 23 and the exposed surface of the substrate 21 by performing a gate oxidization. Subsequently, a polysilicon 25 is formed in the groove part covered by the gate oxide film 24, on the surface of the substrate and on the field oxide film 22. Then, the polysilicon 25 is removed in such a manner that the polysilicon 25 will be left in the groove part only as gate electrode by performing a mechanochemical polishing method. Subsequently, the unnecessary part of the gate oxide film 24 is removed in such a manner that the film 24 will be left at the groove part only. Then, ions are implanted using the ordinary method, and then an annealing is performed. As a result, a source and drain diffusion layer 27 is formed on the silicon substrate 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for manufacturing a silicon MO8 type semiconductor device.

(Prior Art) FIG. 1 shows a process for forming a dirt electrode/source/drain diffusion layer of a conventional silicon f-)MO8 type semiconductor device. In FIG. 1(a), reference numeral 11 is a silicon substrate. First, a field oxide film 12 is selectively formed on the surface of the substrate 11 by the LOCO8 process. Next, a dirt oxide film 13 is formed by oxidation on the exposed surface of the silicon substrate 11, that is, the active region, as shown in FIG. 1(b), and the entire surface becomes an r-) electrode. Polysilicon 14' is deposited at 1 cVD. Thereafter, the polysilicon 14 is buttered to leave only the portion that will become the dirt electrode as shown in FIG. leave. Thereafter, ion implantation 15e into the silicon substrate 11 is performed to form source/drain diffusion layers. Then, when annealing is performed after that, the first
As shown in Figure (d), source/drain diffusion layers 16 are formed.

When forming a shallow junction with low resistance using this method, the ion species to be implanted have high solid solubility in silicon.
In addition, it is necessary to select a description of the diffusion rate in silicon during the subsequent annealing. In this sense, As is suitable as a nu ion species, but there is no ion species suitable as a p-type ion species, making it extremely difficult to form a shallow junction. Furthermore, it is necessary to reduce the depth of the n-type diffusion layer using As, but this is extremely difficult with conventional processes.

(Object of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can form a junction with low resistance and an effective shallow junction depth.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In FIG. 2(a), 21 is a silicon substrate, and first, a field oxide film 22 is selectively formed on the surface of this substrate 21 by the LOCO8 process.

Next, a groove 23 is formed at a predetermined depth in a predetermined portion of the exposed surface of the silicon substrate 21, that is, in the active region, by a die process, as shown in FIG. 2(b).

Thereafter, r-) oxidation is carried out to completely form a Kate fermented film 24 on the inner wall of the groove 23 and the exposed surface of the substrate 11, as shown in FIG. 2(c). Subsequently, polysilicon 25 is deposited on the entire surface of the substrate 21, specifically, on the groove portion covered with the oxide film 24, the substrate surface, and the field oxide film 22, as shown in FIG. 2(e). Form.

After that.

The polysilicon 25 is removed by mechanochemical polishing so that the polysilicon 25 remains only in the groove as a gate electrode, as shown in FIG. 2(d). Subsequently, unnecessary portions of the dirt oxide film 24 are also removed so that they remain only in the grooves, as shown in FIG. 2(d). Thereafter, silicon ion implantation 26 and subsequent annealing are performed in a conventional manner. As a result, a source/drain diffusion layer 27 is formed in the silicon substrate 21 as shown in FIG. 2(d).

In addition, in the above method, the mechanochemical polishing method is a method that simultaneously performs chemical nitching and physical polishing using an etching solution during normal polishing. This is a method that allows you to obtain

(Effects of the Invention) As is clear from the above embodiment, the method of the present invention uses a combination of selective etching of the dirt region in the active region and the mechanochemical IJ tushing method. A gate electrode is formed. Therefore, when forming the diffusion layer of the source train 4, it becomes possible to form the effective junction depth 75 to be shallow. At the same time, since the actual bond can be formed deep, it is possible to form a low-resistance bond.

Furthermore, forming a semi-buried dirt electrode is an effective technique in terms of flattening the device. In addition, reducing the effective junction depth can suppress the short channel effect that occurs when the MO8 element is made smaller, and prevent bunch-through that occurs when the cable length is shortened. This greatly contributes to the realization of ultra-high density MO3IC.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a step of forming a dirt electrode/source/drain diffusion layer of a conventional silicon FMO8 type semiconductor device, and FIG. 2 is a cross-sectional view showing an embodiment of the method for manufacturing a semiconductor device of the present invention. . 21...Silicon substrate, 23...Groove, 24...r
-) Oxide film, 25... polysilicon, 26... ion implantation. 27... Source/drain diffusion layer. Patent applicant Oki Electric Industry Co., Ltd. Figure 1 Figure 2-33:

Claims (1)

[Claims] A step of forming a groove to a predetermined depth in a portion of a silicon substrate that will become a dirt region, a step of forming a dirt e-oxide film on the inner wall of the groove and the surface of the substrate, and a step of forming a groove portion covered with the dirt oxide film and A process of forming polysilicon on the surface of the substrate, a process of leaving the polysilicon only in the trench by mechanochemical polishing, and a process of forming source/drain diffusion layers in silicone by ion implantation and annealing. A method of manufacturing a semiconductor device comprising: