KR100305641B1 - Semiconductor element formed on SOH substrate and its manufacturing method - Google Patents

Abstract

The present invention discloses a semiconductor device formed on an SOI substrate capable of improving electrostatic discharge characteristics and a method of manufacturing the same. The present invention discloses a method of forming a trench-type first field oxide film protruding a predetermined height into a silicon substrate in a silicon substrate, forming a silicon layer on the silicon substrate and the trench-type field oxide film, and a phase first field. Forming a second field oxide film to have a width narrower than the width of the first field oxide film in the silicon layer on the oxide film, to form a U-shaped field oxide film, and to contact the silicon layer on both sides of the field oxide film. And forming a MOS transistor of a type opposite to that of the impurity region in the silicon layer between the field oxide film.

Description

Semiconductor element formed on SOH substrate and its manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a semiconductor device and a method for manufacturing the same.

In general, a silicon on insulator (SOI) substrate is provided as a substrate for forming devices of low power and high speed by preventing RC delay time due to parasitic capacitance of a semiconductor device and leakage current in a junction region.

The SOI substrate is manufactured by attaching a device substrate and a handling substrate on which an insulating film is formed, and a SIMP (seperation by implanted oxygen) method in which oxygen ions are deeply implanted and formed in a silicon substrate.

1 is a cross-sectional view showing a semiconductor device formed on a conventional SOI substrate. As shown, an SOI substrate 100 is provided which is comprised of a handling substrate 1, an insulating layer 2, and a silicon layer 3 on which elements are to be formed. Here, the silicon layer 3 is a layer doped with impurities of the first conductivity type, and is formed to have a thickness of 300 to 1500 kPa to prevent punch through and short channel effects of the MOS transistor formed on the SOI substrate. A field oxide film 4 for defining an active region in a predetermined portion of the silicon layer 3 is formed by a known LOCOS method. At this time, the field oxide film 4 is formed in contact with the insulating layer 2, whereby the active region in which the element is formed is completely separated. A gate electrode 6 having a gate oxide film 5 is formed on the active region of the silicon layer 3. The source / drain regions 7 are formed by ion implantation of impurities of the second conductivity type into the silicon layer regions on both sides of the gate electrode 6. In this case, the source / drain region 7 is formed to contact the insulating layer 2, so that the junction capacitance and the leakage current are not generated.

An interlayer insulating film 8 is deposited to a predetermined thickness over the entirety of the resultant, and then etched to expose the source / drain regions 7 and then metal contacted with the source / drain regions 7. The wiring 9 is formed.

However, the semiconductor device on the SOI substrate is promising as a low voltage device due to the small junction capacitance, but the electrostatic discharge (ESD) characteristics are very weak.

That is, in a conventional semiconductor device, an antistatic circuit composed of NMOS transistors or CMOS transistors is formed in a silicon substrate to protect an internal circuit when static electricity flows from the outside, and discharges the static current through the grounded well or source electrode. I am trying to.

In contrast, in the MOS transistor formed on the SOI substrate, since the source / drain region of the MOS transistor contacts the buried oxide film, that is, the insulating layer, the electrostatic current introduced into the device is difficult to escape to the edge of the junction. Current is concentrated and heat is generated as compared with bulk devices. In addition, heat is generated as the injected charges are discharged to the ground, which makes it difficult to easily discharge heat.

Accordingly, an object of the present invention is to provide a semiconductor device formed on an SOI substrate that can improve the ESD characteristics, and a method for manufacturing the same.

1 is a cross-sectional view of a semiconductor device formed on a conventional SOH substrate.

2A to 2I are cross-sectional views of respective processes for explaining a method of manufacturing a semiconductor device formed on an SOI substrate according to the present invention.

(Explanation of symbols for the main parts of the drawing)

10-silicon substrate 11a-field oxide film

12-Oxide 13-Silicon Layer

14,14a, 18-photoresist pattern 15-impurity region

16-gate oxide 17-gate electrode

19-source, drain area

A semiconductor device formed on an SOI substrate according to an aspect of the present invention for achieving the above object, the silicon substrate; A silicon layer laminated on the silicon substrate; A field oxide film formed in the silicon substrate and the silicon layer in a “凸” shape to define an active region where a semiconductor device is to be formed; A gate electrode formed on the active region of the silicon layer defined by the field oxide film; Source and drain regions formed in the silicon layers on both sides of the gate electrode; And an impurity region formed at an interface between the silicon substrate and the silicon layer between the field oxide film and having a type opposite to that of the source and drain regions.

In addition, a method of manufacturing a semiconductor device formed on an SOI substrate according to another aspect of the present invention for achieving the above object, the trench-type first field so as to protrude by a predetermined height from each surface in the predetermined region of the silicon substrate; Forming an oxide film; Forming a silicon layer on the silicon substrate and the trench-type first field oxide films; Forming a second field oxide film having a width narrower than the width of the first field oxide film in a silicon layer region over the first field oxide film, thereby forming field oxide films having a “凸” shape; Forming an impurity region in a silicon substrate region in contact with a silicon layer region between the field oxide films; And forming a MOS transistor of a type opposite to the impurity region in a silicon layer region between the field oxide layers.

The forming of the first field oxide layer may include forming a trench by etching a predetermined portion of the silicon substrate by a predetermined depth; Buried oxide in the trench; Forming an oxide film on the trench oxide and the silicon substrate by a predetermined thickness; And etching the oxide layer so as to remain only on the trench oxide.

The silicon layer is formed by crystal growth of the silicon substrate.

In addition, the forming of the field oxide film having the “VIII” structure may include forming a photoresist pattern on the silicon layer to expose a predetermined portion of the first field oxide film; Etching a predetermined portion of the silicon layer and the first field oxide layer using the photoresist pattern as a mask to form a hole; Forming an oxide film on the resultant portion so that the hole is sufficiently buried; Removing the oxide film on the silicon layer so as to embed the oxide film in the hole.

In addition, the forming of the impurity region may be performed by ion implantation of impurity ions and germanium ions constituting the impurity region, or ion implantation of impurity ions and argon or nitrogen atoms constituting the impurity region together.

The forming of the MOS transistor may include forming a gate electrode on a predetermined portion of an upper portion of the silicon layer between the field oxide layers; And forming a source and a drain region by ion implanting impurities of a type opposite to that of the impurity region into the silicon layer between the sidewall of the gate electrode and the field oxide layer.

According to the present invention, in a SOI substrate formed of a stacked structure of a silicon substrate and a silicon layer, a field oxide film is formed in a “凸” shape to surround the active region, and an impurity region is formed in the silicon substrate between the field oxide films. do. Accordingly, the electrostatic current generated in the semiconductor element can be easily dispersed through the impurity region, so that the electrostatic current is easily released, thereby eliminating the phenomenon of heat generation due to current concentration.

(Example)

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2I are cross-sectional views of respective processes for explaining a method of manufacturing a semiconductor device formed on an SOI substrate according to the present invention.

First, as shown in FIG. 2A, a trench (not shown) is formed by etching a predetermined depth of the silicon substrate 10, for example, about 100 microseconds, and then embedding an oxide film in the trench to form a first field oxide film. (11) is formed.

Next, as shown in FIG. 2B, the oxide film 12 is formed on the first field oxide film 11 and the silicon substrate 10 at about 5 to 15 kV.

Thereafter, as shown in FIG. 2C, a first photoresist pattern (not shown) is formed by a known photolithography process so as to cover the field oxide film 11 portion on the oxide film 12, and then the first photo. The exposed portion of the oxide film 12 is etched using the resist pattern as a mask. Accordingly, the height of the first field oxide film 11 protrudes from the surface of the silicon substrate 10 by a predetermined thickness, and the active region where the semiconductor element is to be formed is defined. Then, the surface of the resultant crystal is grown, and the silicon substrate 10 is crystal grown on the silicon substrate 10 and the field oxide film 11 to form a crystal growth silicon layer 13.

Next, as shown in FIG. 2D, the second photoresist pattern 14 may be exposed to a predetermined portion of the first field oxide film 11 on the silicon layer 13 using a known photolithography process. To form. At this time, the width exposed by the second photoresist pattern 14 is smaller than the width of the first field oxide film 11. Thereafter, the crystal growth silicon layer 13 is patterned using the second photoresist pattern 14 as a mask to form a hole h for opening a predetermined portion of the field oxide film 11.

Subsequently, as shown in FIG. 2E, the second photoresist pattern 15 is removed, and subsequently, as shown in FIG. 2F, the oxide layer is sufficiently embedded in the hole h on the silicon layer 13. After depositing, the oxide film is polished by an etch back or chemical mechanical polishing process so that the surface of the silicon layer 13 is exposed to form a second field oxide film 11 'in the hole h. As a result, the field oxide film 11a having a "凸" structure is finally formed.

Subsequently, as shown in FIG. 2G, a third photoresist pattern 14 covering the field oxide film 11a is formed on the resultant through a known photolithography process. That is, the third photoresist pattern 14a is formed to have the same width as or slightly larger than the width of the first field oxide film 11. Subsequently, using the third photoresist pattern 14a as an ion implantation mask, ion implantation at high concentration into the region of the silicon substrate 10 on both sides of the field oxide film 11a, for example, is performed, In the impurity region 15 is formed. At this time, when implanting ions to form the impurity region 15, in order to reduce the thickness of the impurity region 15, germanium ions are added to the P-type impurity, or argon or inert atom is an inert atom. Can be added. Since the impurity region 15 is formed on the silicon substrate 10 in contact with the silicon layer 11, it is possible to prevent the silicon layer 11 from floating from the silicon substrate 10. Through the electrostatic current can be discharged.

Thereafter, as shown in FIG. 2H, the gate oxide film 16 and the gate electrode 17 are formed by a known method in a predetermined portion of the crystalline silicon layer 13 between the field oxide films 11a.

Subsequently, as shown in FIG. 2I, a fourth photoresist pattern 18 is formed on the gate electrode 17 to cover the exposed field oxide film 11a. Next, for example, an N-type impurity is ion-implanted into the exposed crystalline silicon layer to form a source and drain region 19. As a result, a MOS transistor is formed on the SOI substrate.

In the present invention, the field oxide film 11a is formed in a "凸" shape to completely separate the active regions, and to prevent the substrate floating phenomenon on the silicon substrate 10 under the active regions between the field oxide films 11a. An impurity region 15 serving as a contact is formed. Accordingly, even if the source and drain regions are in contact with the field oxide film, the ESD current generated in the semiconductor element is easily discharged through the impurity region 15.

In addition, this invention is not limited only to the above-mentioned embodiment. For example, in the present embodiment, the impurity region is P-type and the source and drain are N-type, but the same effect can be obtained even if it is changed to this.

As described in detail above, according to the present invention, a SOI substrate having a stacked structure of a silicon substrate and a silicon layer is formed in a U-shaped cross section so as to surround the active region, and is floated between the field oxide films. An impurity region is formed in the silicon substrate. Accordingly, the electrostatic current generated in the semiconductor device can be easily discharged to the outside through the impurity region, so that the heat generation phenomenon due to the concentration of the electrostatic current can be eliminated, thereby securing the device characteristics. .

In addition, this invention can be implemented in various changes within the range which does not deviate from the summary.

Claims (8)

Silicon substrates; A silicon layer laminated on the silicon substrate; A field oxide film formed in the silicon substrate and the silicon layer in a “凸” shape to define an active region where a semiconductor device is to be formed; A gate electrode formed on the active region of the silicon fin defined by the field oxide film; Source and drain regions formed on both sides of the gate electrode and in the silicon layer; And And a semiconductor device formed at an interface between the silicon substrate and the silicon layer between the field oxide film and an impurity region having a type opposite to that of the source and drain regions. Forming a trench-type first field oxide film in predetermined regions of the silicon substrate to protrude from the substrate surface by a predetermined height, respectively; Forming a silicon layer on the silicon substrate and the trench type field oxide layer; Forming a field oxide films having a U-shaped structure by forming a second field oxide film in the silicon layer region above the first field oxide film to have a width narrower than the width of the first field oxide film; Forming an impurity region in a silicon substrate region in contact with a silicon layer region between the field oxide films; And And forming a MOS transistor of a type opposite to that of the impurity region in the silicon layer region between the field oxide films. The method of claim 2, wherein the forming of the first field oxide layer comprises: forming trenches by etching predetermined regions of the silicon substrate by a predetermined depth; Buried oxide in the trench; Forming an oxide film on the trench oxide and the silicon substrate by a predetermined thickness; And etching the oxide layer so that only the trench oxide remains on the trench oxide. The method of claim 2, wherein the forming of the silicon layer is performed by crystal growing the silicon substrate. The method of claim 2, wherein forming a field oxide film having a U-shaped structure comprises: forming a photoresist pattern on the silicon layer to expose a predetermined portion of the first field oxide film; Etching the exposed silicon layer portion and the first field oxide layer portion below the photoresist pattern as a mask to form a hole; Forming an oxide film on the resultant so that the hole is sufficiently buried; And removing the oxide film on the silicon layer so that the oxide film remains only in the hole. 3. The method of claim 2, wherein in the forming of the impurity region, ion implantation is performed while adding germanium ions when ion implantation of the impurity ions forming the impurity region. The method of claim 2, wherein in the forming of the impurity region, impurity ions constituting the impurity region and argon or nitrogen atoms are ion-implanted together. The method of claim 2, wherein the forming of the MOS transistor comprises: forming a gate electrode on a silicon layer region between the field oxide layers; And forming a source and a drain region by ion implanting impurities of a type opposite to that of the impurity region into silicon regions on both sides of the gate electrode.