KR20050009901A - Method of forming silicon quantum dot for semiconductor device - Google Patents

Abstract

PURPOSE: A method for forming a silicon quantum dot of a semiconductor device is provided to obtain a good characteristic of a device and guarantee a stable operation characteristic of a silicon quantum dot by forming the silicon quantum dot having a proper size of 10 nanometers or lower and uniformity while using fluorine ions. CONSTITUTION: An oxygen ion layer is formed in a silicon substrate(10). The substrate is patterned to expose the surface of the oxygen ion layer so that a silicon quantum dot(10A) having the first size is formed. The silicon quantum dot and the oxygen ion layer are oxidized to reduce the silicon quantum dot to the second size smaller than the first size so that the substrate is separated from the silicon quantum dot. The second oxide layer(13) is formed on the first oxide layer(12B). Fluorine ions are implanted into the first and second oxide layers. A gate material layer is deposited on the second oxide layer while the silicon quantum dot is oxidized to be reduced to the third size smaller than the second size.

Description

Silicon quantum dot formation method of a semiconductor device {METHOD OF FORMING SILICON QUANTUM DOT FOR SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor device manufacturing technology, and more particularly, to a method of forming silicon quantum dots in a semiconductor device.

The development of non-volatile memory devices is applying silicon quantum dots as the development of nano technology is urgent due to the ultra-high integration and ultra-high speed of semiconductor devices.

Silicon quantum dots are formed in an island form on the oxide layer by using a lithography process and an etching process, or by implanting silicon ions into the oxide layer and performing heat treatment at a high temperature of about 1000 ° C. or more.

On the other hand, in order for silicon quantum dots to operate stably at room temperature, it is important to secure a size and uniformity of about 10 nm or less. However, in case of applying lithography and etching process, it is easy to secure uniformity but only 100nm size quantum dots can be formed, so it is difficult to secure proper size.In case of applying ion implantation and heat treatment, quantum dots below 10nm are formed. Yes, but it is difficult to ensure uniformity.

The present invention has been proposed to solve the above problems of the prior art, and provides a method for easily forming a silicon quantum dot having an appropriate size and uniformity of 10 nm or less in the manufacture of a semiconductor device. have.

1A to 1F are cross-sectional views illustrating a method of forming silicon quantum dots in a semiconductor device according to an embodiment of the present invention.

2A and 2B show changes in bonding of oxide films during F ion implantation.

3 is a graph showing a comparison between gate voltage (Vg) and drain current (Id) characteristics when and without implantation of F ions;

※ Explanation of symbols for main parts of drawing

10: semiconductor substrate 10A: silicon quantum dots

11: pad oxide film 12: oxygen ion

12A: oxygen ion layer 12B: first oxide film

13: 2nd oxide film 14: F ion

15: metal film

According to an aspect of the present invention for achieving the above technical problem, the object of the present invention is the step of forming an oxygen ion layer in the silicon substrate; Patterning the substrate to expose the surface of the oxygen ion layer to form a silicon quantum dot having a first size; Oxidizing the silicon quantum dots and the oxygen ion layer to reduce the silicon quantum dots to a second size smaller than the first size and simultaneously forming a first oxide film to separate the substrate from the silicon quantum dots; Forming a second oxide film on the first oxide film; Implanting fluorine ions into the first and second oxide films; And depositing a gate material layer on the second oxide layer and simultaneously oxidizing the silicon quantum dots to reduce the silicon quantum dots to a third size smaller than the second size.

Here, the first size of the silicon quantum dots is about 100 nm, the second size is about 40-50 nm, and the third size is about 10 nm or less.

Hereinafter, preferred embodiments of the present invention will be introduced in order to enable those skilled in the art to more easily carry out the present invention.

1A to 1F are cross-sectional views illustrating a method of forming silicon quantum dots in a semiconductor device according to an embodiment of the present invention.

As shown in FIG. 1A, a pad oxide film 11 is formed on a silicon substrate 10, and oxygen ions 12 are injected into the substrate 10 to form an oxygen ion layer 12A in the substrate 10. . Next, as shown in FIG. 1B, the pad oxide layer 11 is removed, and the substrate 10 is patterned so that the surface of the oxygen ion layer 12A is exposed by lithography and etching to form a first substrate having a thickness of about 100 nm. A silicon quantum dot 10A having a size S1 is formed uniformly.

As shown in FIG. 1C, the silicon quantum dot 10A and the oxygen ion layer 12A are oxidized by an oxidation process to reduce the silicon quantum dot 10A to a second size of about 40 to 50 nm, and at the same time, A first oxide film 12B surrounding 10A is formed to separate the substrate 10 and the silicon quantum dots 10A. Next, as shown in FIG. 1D, a second oxide film 13 is formed on the first oxide film 12B so as to fill the space between the first oxide films 12B.

As shown in FIG. 1E, after implanting F ions 14 into the first and second oxide films 12B and 13, as shown in FIG. 1F, as a gate material on the second oxide film 13. While depositing the metal film 15, the silicon quantum dots 10A are oxidized to reduce the silicon quantum dots 10A to a third size S3 of 10 nm or less.

That is, due to the diffusion of the F ions implanted into the oxide films 12B and 13, as illustrated in FIGS. 2A and 2B, the F ions are separated from the silicon-oxygen (Si-O) bonds in the oxide films 12B and 13. Substitute O to separate O, and the separated O is not shown, but combines with Si of silicon quantum dot 10A to oxidize silicon quantum dot 10A again to reduce the size of silicon quantum dot 10A to 10 nm or less. 3 sizes (S3) can be reduced.

According to the above embodiment, silicon quantum dots can be uniformly formed to an appropriate size of 10 nm or less by implanting F ions into the oxide film in parallel with the patterning process by the photolithography and etching process and the ion implantation and oxidation process. Quantum dots can operate stably at room temperature.

In addition, when the transistor is manufactured by applying the silicon quantum dots, characteristics such as mobility, hot carrier, and gate induced drain leakage (GIDL) of the transistor are improved by the F ions implanted in the oxide film. As a result, as shown in Fig. 3, excellent current characteristics can be obtained.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

In the present invention described above, the silicon quantum dots are formed to have an appropriate size and uniformity of 10 nm or less by applying F ions, thereby ensuring stable operating characteristics of the silicon quantum dots and obtaining excellent device characteristics.

Claims (4)

Forming an oxygen ion layer in the silicon substrate; Patterning the substrate to expose the surface of the oxygen ion layer to form a silicon quantum dot having a first size; Oxidizing the silicon quantum dots and the oxygen ion layer to reduce the silicon quantum dots to a second size smaller than the first size and simultaneously forming a first oxide film to separate the substrate from the silicon quantum dots; Forming a second oxide film on the first oxide film; Implanting fluorine ions into the first and second oxide films; And Depositing a gate material layer on the second oxide layer and simultaneously oxidizing the silicon quantum dots to reduce the silicon quantum dots to a third size smaller than the second size. The method of claim 1, Wherein the first size of the silicon quantum dots is about 100 nm. The method according to claim 1 or 2, Wherein the second size of the silicon quantum dots is about 40 to 50 nm. The method of claim 3, wherein And the third size of the silicon quantum dots is about 10 nm or less.