KR100222435B1 - Method for manufacturing layer for use in semiconductor device - Google Patents

Abstract

The noble method of manufacturing an active layer and a compound film on a substrate to fabricate a semiconductor device comprises the steps of forming an amorphous silicon film on the substrate, implanting impurity ions into the interior from an upper surface of the amorphous silicon film to a set depth; By scanning a beam having an energy density set on the upper surface, the lower region where impurity ions are not generally implanted in the amorphous silicon film is changed into a polysilicon film and at the same time, impurity ions are deposited in the amorphous silicon film. And implanting a region near the upper surface into a compound film related to the impurity ions, thereby forming the polysilicon film as an active layer, and forming a compound film related to the impurity ions as the compound insulating film.

Description

METHODS FOR MANUFACTURING LAYER FOR USE IN SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device film, and more particularly, to a method for easily manufacturing an active layer and a compound film on a substrate so as to fabricate a semiconductor device.

As the active layer on the substrate for manufacturing a semiconductor device, polysilicon, which is usually polycrystalline, is superior to that of amorphous silicon and is used more.

Recently, as the new century of communication is expected, attention is focused on the development of high definition systems (HDS), and polysilicon is attracting attention as a semiconductor material of devices used in this field. HDS covers a wide range of fields, including capturing, processing and transmitting information, receiving and reflecting information. The cutting-edge technologies that must accompany HDS will be recycled in a series of ways to create and develop new high-end brain products for aerospace, military, education and medicine.

The development project in the field of display forms one of the core points of the above-described HDS. Such advanced technologies have a bright market prospect because they are directly connected to portable computers, workstations, and high definition televisions (HDTVs). The mainstream display technology tends to be focused on thin film transistors (TFTs) -liquid crystal displays (LCDs) using the characteristics of transistors and liquid crystals in thin films.

Japan has already developed TFT-LCD technology using amorphous silicon TFT and is in mass production. The recent negotiations between SHARP in Japan and IBM in the US prove this. Domestic related companies are also in the process of developing by introducing amorphous silicon TFT process technology. Domestic related companies prefer to apply amorphous silicon TFT process technology to flat panel displays of portable computers such as laptops and notebook computers, while accumulating the necessary technology for HDTV displays. On the other hand, business interest in transistors (eg, poly-silicon TFTs) in polycrystalline silicon thin films is increasing day by day. This is because the polysilicon TFT has various superior performances compared to the amorphous silicon TFT. In particular, high-speed operation and CMOS possibilities enable integrated drive circuit processing, which means less display panel fabrication steps, resulting in higher process yields and lower system assembly costs. In addition, the abundant amount of current accompanying high mobility provides gray-scale full color images to improve the displayed image quality.

As described above, the polysilicon TFT, which is a polycrystalline TFT, has various superior performances compared to the amorphous silicon TFT, but the development speed is slow because it requires enormous manufacturing equipment as compared to the amorphous silicon TFT. However, due to the intrinsic advantages of polysilicon TFTs, research on the structure of devices and investment in manufacturing facilities have been gradually increasing.

As described above, it can be seen that polycrystalline TFTs (Polycrystalline Silicon Thin Film Transistors) are widely used in active matrix liquid crystal displays (AMLCDs), that is, display fields.

By the way, in order to manufacture such a polysilicon TFT, the work of making an active layer (polysilicon film) and a compound film (mainly an oxide film) on the substrate must basically be accompanied. As one of these operations, oxidation by chemical vapor deposition (CVD) is conventionally employed to produce a gate insulating film of a polysilicon TFT device manufactured at a relatively low temperature. Oxidation for polysilicon TFTs is a process that is required to have low leakage current, high dielectric strength, and good interface (interface) with the polysilicon layer. In addition to making the gate insulating film, crystallization of the polysilicon active layer is another important issue. Crystallization by pulsed excimer laser irradiation can be used as a promising means for producing polysilicon TFTs on inexpensive glass substrates. However, the surface roughness of the polysilicon layer crystallized by this excimer laser becomes rougher as the pulse laser energy density increases, and breakdown, which is a characteristic that is exhibited by CVD oxidation, for example, leakage current or breakdown characteristics The electric field characteristics are undesirable as characteristics for high performance polysilicon TFT elements. Therefore, the active layer of polysilicon is required to have flat surface roughness and good electrical properties, and the oxide film needs to be of high quality so as to have a good interface with the polysilicon active layer.

Conventionally, an amorphous amorphous silicon is deposited on a substrate and then annealed using a high temperature process of 600 ° C. or higher to make it into a polysilicon layer. Then, a gate oxide film was formed on the polysilicon layer through atmospheric chemical vapor deposition. Therefore, it was difficult to obtain flat surface roughness of the active layer of polysilicon by the high temperature process, and also did not have good electrical properties. Moreover, since the process of making an active layer (polysilicon film) and a compound film (mainly an oxide film) on the substrate is completed by performing two steps in order, there is a problem that it takes a considerable time to complete the film production process.

Accordingly, it is an object of the present invention to provide a method for easily manufacturing an active layer and a compound film on a substrate so as to fabricate a semiconductor device.

Another object of the present invention is to provide a method for simultaneously producing an active layer and a compound film on a substrate in a simple process.

It is still another object of the present invention to provide a method for reducing the surface roughness on the top of the active layer so that a good interface is obtained between the active layer formed on the substrate and the compound film.

1 to 3 are cross-sectional views of a manufacturing process sequentially showing a method of manufacturing an active layer and a compound film on a substrate according to an embodiment of the present invention.

4 is a graph showing a change in the interface roughness between the active layer and the compound film of FIG. 3 according to the change of the density of laser energy.

5 is a graph showing breakdown electric fields of oxide films prepared according to one embodiment of the present invention in comparison with those of oxide films produced by conventional methods.

In order to achieve the above object, a method of manufacturing an active layer and a compound insulating film on the substrate to manufacture a semiconductor device comprising the steps of: forming a semiconductor film on the substrate to be a material of the active layer and the compound insulating film;

Ion implanting impurity ions which form a component of the compound insulating film into the depth up to a set depth from an upper surface of the semiconductor film by an ion implantation method;

By irradiating the laser beam having the energy density set on the upper surface in full, the electrical characteristics of the lower region where impurity ions are not generally injected into the semiconductor film are changed, and the impurity ions are generally injected into the semiconductor film. Causing the region near the upper surface to be changed into the compound insulating film associated with the impurity ions, and simultaneously forming the lower region with the changed electrical properties as the active layer of the semiconductor element as the compound insulating film as the compound insulating film. It is characterized by having.

Hereinafter, a method for manufacturing a film according to a preferred embodiment of the present invention will be described with the accompanying drawings. Areas or parts having the same functions as each other in the accompanying drawings are labeled with the same or similar reference numerals for ease of understanding. In the following description, specific details are set forth by way of example and in detail in order to provide a more thorough understanding of the present invention. However, for those skilled in the art, the present invention may be practiced only by the above description without these details. In addition, the basic physical and electrical properties, and operations of materials so well known in the art are not described in detail in order not to obscure the subject matter of the present invention.

The film of the present invention described above can be applied not only to thin film transistors but also to general MOS transistors in view of application. In addition, various compound films may be manufactured by implantation of impurity ions, and may be applied to CMOS or power transistors in which N-type and P-type transistors are formed on the same substrate.

Therefore, in the following description, a preferred embodiment of the present invention is limited to the film of the device of the thin film transistor and will be described by way of example with reference to the accompanying drawings.

1 to 3 are cross-sectional views of a manufacturing process sequentially showing a method of manufacturing an active layer and a compound film on a substrate according to an embodiment of the present invention in order of the process. According to the order of processes to be described below, it will be appreciated that the formation of the gate oxide film and the crystallization of the polysilicon active layer are simultaneously performed. The manufacturing sequence according to one embodiment of the presented method is described by way of example below.

First, referring to FIG. 1, after the amorphous silicon film 4 is formed on the glass substrate or the silicon wafer 2, it is shown that ion implantation is performed. The amorphous silicon film 4 is formed by LPCVD at about 550 degrees Celsius, in which case it is desirable to deposit at a thickness of about 3000 Angstroms. Subsequently, 5 * 10 ¹⁷ cm ^-2 concentration of oxygen ions is implanted into the deposited energy 10KeV into the deposited amorphous silicon film 4. Then, oxygen, which is impurity ions, is injected into the depth from the upper surface of the film 4 to the set depth.

In the process of FIG. 2, the laser emission of the excimer laser is irradiated to the ion implanted amorphous silicon film 4 with the energy density in the range of 254 mJ / cm ² to 371 mJ / cm ² . As a result, the near-surface region 41 in the amorphous silicon film 4 is changed into the oxide film 41S in FIG. 3 and the lower region 40 is changed to the polysilicon film 40P. Because the implanted oxygen ions are located approximately 41 near the surface of the amorphous silicon film 4, the oxygen ions in the region near the surface are excited by the energy of the irradiated laser beam to form silicon atoms in the amorphous silicon film. To form a silicon oxide (SiO 2) film. In addition, the amorphous silicon region in the lower 40 of the near-surface region is crystallized by the laser energy and changed into a polysilicon film 40P that is polycrystalline. Here, the polysilicon film 40P is used as an active layer because it is changed into a layer having good electrical conductivity, and the silicon oxide film is used as a compound film. In this way, the formation of the oxide film and the crystallization to the polysilicon film are simultaneously performed by the operation of the excimer laser emission, thereby simplifying the manufacturing process. In this embodiment described above, an amorphous silicon film was formed on the substrate to obtain a silicon oxide film and a polysilicon film. However, an upper region was formed as a nitride film by forming a normal silicon film on the substrate, implanting nitrogen ions, and then irradiating a laser beam. The lower region can be obtained as an active layer whose electrical properties have changed.

Hereinafter, the oxide film obtained by the above manufacturing method is referred to as LI ² Ox (LASER induced implanted oxide) for convenience of explanation. 4 is a graph showing the change of the interface roughness between the active layer 40P and the compound film 41S of FIG. 3 according to the change of the density of laser energy. Here, the rectangular point CONV represents the interface roughness produced by the conventional method. Referring to the graph, the conventional surface roughness is about 111 Angstroms, whereas the average surface roughness of this embodiment is about 23 Angstroms. Circular points P1-P4 show the change in surface roughness with respect to the laser energy density, respectively. Therefore, according to the present embodiment, since the surface roughness is flattened by about five times as compared with the conventional one, there is an effect that the electrical characteristics such as leakage current or breakdown electric field become better.

5 is a graph showing a breakdown electric field of an oxide film prepared according to an embodiment of the present invention compared with that of an oxide film produced by a conventional method. When the horizontal axis represents the electric field and the vertical axis represents the density of the current, line number 50 represents the characteristic according to the embodiment of the present invention, and line number 51 represents the characteristic by conventional dry oxidation. In addition, the line number 52 indicates the characteristic by the conventional APCVD oxidation.

According to the present invention as described above, the active layer and the compound film on the substrate can be easily manufactured in a simple process, as well as there is an advantage that can be simultaneously produced the active layer and the compound film. In addition, since the surface roughness is very flat between the active layer and the compound film to obtain a good interface, there is an effect of ensuring the reliability of the electrical properties of the fabricated device.

Although the above-described invention has been described and limited by way of example with reference to the drawings, the same will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. For example, it is possible to use any of grass, sapphire, amorphous silicon or polycrystalline silicon as a substrate in terms of materials, and in application, it is applicable to general MOS transistors as well as thin film transistors. It is also found that a nitride film or another compound film other than an oxide film can be obtained arbitrarily by implantation of impurity ions.

Claims (8)

In the method of manufacturing the active layer and the compound insulating film on the substrate so as to produce a (corrected) semiconductor device: Forming a semiconductor film on the substrate to be a material of the active layer and the compound insulating film; Ion implanting impurity ions which form a component of the compound insulating film into the depth up to a set depth from an upper surface of the semiconductor film by an ion implantation method; By irradiating the laser beam having the energy density set on the upper surface in full, the electrical characteristics of the lower region where impurity ions are not generally injected into the semiconductor film are changed, and the impurity ions are generally injected into the semiconductor film. Causing the region near the upper surface to be changed into the compound insulating film associated with the impurity ions, and simultaneously forming the lower region with the changed electrical properties as the active layer of the semiconductor element as the compound insulating film as the compound insulating film. Characterized by having. The method of claim 1, wherein the impurity ions are oxygen or nitrogen. The method of claim 2, wherein the substrate is made of glass or silicon. 4. The method of claim 3 wherein the beam has an energy density 255mJ / cm ² - Method according to claim balsaengdoem from the excimer which emits laser light so 370mJ / cm ² laser. The method of claim 4, wherein the semiconductor device is a thin film transistor. 6. The method of claim 5, wherein the semiconductor film is formed by LPCVD at about 550 degrees C and has a thickness of about 3000 Angstroms when the silicon film is an amorphous silicon film. The method of claim 2, wherein the oxygen ion is implanted into the semiconductor film at an implantation energy of about 10 KeV at a concentration of 5 * 10 ¹⁷ cm ^-2 . The method of claim 6, wherein the active layer of the lower region is made of polysilicon.