KR20030055940A - Method for fabricating of semiconductor device - Google Patents

Abstract

PURPOSE: A method for manufacturing a semiconductor device is provided to be capable of obtaining low resistance and good thermal stability by increasing the area of a gate before forming a salicide. CONSTITUTION: Gate electrodes(23a,23b) are formed on a semiconductor substrate(21). A lightly doped region(24) is formed in the substrate located between the gate electrodes. After forming the first and second insulating layer on the resultant structure, the surface and top sides of the gate electrodes(23a,23b) are exposed. Gate ions are implanted into the exposed gate electrodes. A sidewall mask layer is formed at the top sides of the gate electrode. By sequentially removing the first and second insulating layer using the sidewall mask layer as a mask, the first and second spacer(31,29) are formed at the both sidewalls of the gate electrodes. After removing the sidewall mask layer, a source/drain region is formed. An epitaxial layer(32) is grown on the exposed substrate and gate electrode by selective epitaxial growth. A salicide layer(33) is then formed on the epitaxial layer(32).

Description

Method for fabricating a semiconductor device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of semiconductor devices, and more particularly, to a method of manufacturing a semiconductor device having a low resistance and excellent thermal stability by increasing the gate area by a selective epitaxial growth (SEG) process before proceeding with the salicide process.

In general, in order to form a high-speed semiconductor device, the sheet resistance and the contact resistance of the gate electrode and the source / drain regions should be reduced. For this purpose, a salicide process for forming silicide with low resistivity selectively in the gate electrode and the source / drain regions is widely used.

In particular, salicide gate processes have been widely applied to improve gate characteristics of 1G DRAM or more logic and integrated memory logic (MML) devices.

Hereinafter, the gate electrode formation according to the related art will be described with reference to the accompanying drawings.

1A to 1D are cross-sectional views of a process for forming a gate electrode of the prior art.

As shown in FIG. 1A, the field oxide film 12 is grown in the device isolation region of the semiconductor substrate 11, and then the gate oxide film 13 is formed in the active region of the semiconductor substrate 11.

Subsequently, a polysilicon layer is formed on the gate oxide layer 13 and then selectively patterned to form the gate electrode 14.

In addition, the impurity ions are implanted into the surface of the semiconductor substrate 11 using the gate electrode 14 as a mask to form a low concentration impurity region 15 for forming a lightly doped drain (LDD) region.

Subsequently, as shown in FIG. 1B, a material layer for forming sidewalls is deposited on the entire surface including the gate electrode 14 and the low concentration impurity region 15, and the gate sidewalls are formed on the side of the gate electrode 14 by an anisotropic etching process. 16).

Impurity ions are implanted into the entire surface including the gate sidewall 16 to form source / drain regions 17 in active surfaces on both sides of the gate electrode 14.

Subsequently, as illustrated in FIG. 1C, a material of high melting point metal such as Co and Ti is deposited on the entire surface to form a silicide forming material layer 18.

As shown in FIG. 1D, the silicide forming material layer 18 is silicided to form a salicide layer 19 on the active surface and the top surface of the gate electrode 14, thereby forming unreacted silicide. The material layer 18 is removed.

In the silicide process, the salicide layer may be unevenly formed or agglomerated due to process conditions such as heat treatment.

The non-uniformly formed silicide causes problems such as device defects or leakage currents in the field oxide film.

However, in the gate electrode forming process of the semiconductor device of the prior art, there are the following problems.

The control of agglomeration of the salicide layer (agglomerate) causes problems such as leakage current, and when the junction thickness becomes thinner than 0.1 µm, the problem of leakage in the junction layer itself is also serious due to uneven silicide.

In addition, the resistance of the gate salicide layer is not taken into consideration, which affects the operation speed of the device, and thermal stability is not sufficiently secured, thereby lowering the reliability of the device.

The present invention is to solve the problem of the prior art gate electrode manufacturing process, the semiconductor to increase the gate area by a selective epitaxial growth (SEG) process before the salicide process to have a low resistance and excellent thermal stability It is an object of the present invention to provide a method for manufacturing a device.

1A to 1D are cross-sectional views of a process for forming a gate electrode of the prior art.

2A to 2M are cross-sectional views of a process for forming a gate electrode according to the present invention.

Explanation of symbols for the main parts of the drawings

21. Semiconductor substrate 22. Device isolation layer

23a.23b. Gate electrode 24. Low concentration impurity region

25. First Insulation Layer 26. Second Insulation Layer

26a. Fully planarized second insulating layer 26b. Underpolished Second Insulation Layer

26c. Over-etched Second Insulation Layer 27. Photoresist

28. Third insulating layer 28a. Sidewall mask layer

29. Second gate sidewalls 30. Source / drain regions

31. First gate sidewall 32. Selective epitaxial gate layer

33. Salicide Layer

According to an aspect of the present invention, there is provided a method of fabricating a semiconductor device, the method comprising: forming gate electrodes on a semiconductor substrate; forming a low concentration impurity region in a surface of both substrates of the gate electrodes, and forming a gate electrode on a front surface including the gate electrode; Forming a first and second insulating layers and exposing a portion of the top surface and the top side of the gate electrodes; optionally masking the gate electrodes and performing a gate ion implantation process in the exposed gate electrodes; top of the gate electrode Forming a sidewall mask layer on the side surface and removing the first and second gate sidewalls using a mask to form the first and second gate sidewalls, and then removing the sidewall mask layer; Forming and forming a selective epitaxial growth gate layer on the exposed substrate surface and gate electrode surface. ; Characterized by comprising the step of forming a raised layer side to the surface of the selective epitaxial growth layer gate.

Hereinafter, a method of manufacturing a semiconductor device according to the present invention will be described in detail with reference to the accompanying drawings.

2A to 2M are cross-sectional views of a process for forming a gate electrode according to the present invention.

In the present invention, the SEG process is performed to increase the area of the gate before the gate salicide process.

The SEG process is a technology in which a single crystal silicon substrate is used as a seed layer and silicon is grown thereon in the same crystal direction. Therefore, using this method, the area can be increased by selectively growing silicon only in areas where the silicon is exposed on the surface.

The present invention is to solve the NP bias and active damage caused by the pre-doping of the N + gate during the manufacturing process of the highly integrated CMOS semiconductor device, to lower the resistance of the gate silicide and to improve the thermal stability.

In the fabrication of highly integrated CMOS semiconductor devices, the resistance of poly gate salicides has a great effect on the performance of the devices.

Accordingly, many studies have been conducted to lower the poly gate salicide resistance, and many studies have been conducted to prevent deterioration due to subsequent heat treatment.

First, as shown in FIG. 2A, the device isolation layer 12 is formed on the semiconductor substrate 21 to define regions in which transistors having channels of different conductivity types are formed.

Subsequently, a gate forming material layer is deposited on the entire surface and selectively patterned by a photolithography process to form gate electrodes 23a and 23b.

Lightly doped drain (LDD) ion implantation is performed using the gate electrodes 23a and 23b as a mask to form the low concentration impurity region 24.

Subsequently, as shown in FIG. 2B, a high temperature low pressure deposition (HLD) oxide film or TEOS (Tetra-Ethyl-Ortho-Silicate) is deposited on the entire surface including the gate electrodes 23a and 23b to a thickness of 100 to 400 kPa. As a result, a first insulating layer 25 serving as a buffer layer is formed.

In addition, nitride is deposited on the first insulating layer 25 to a thickness of 2800 to 3200 Å to form a second insulating layer 26.

Subsequently, the second insulating layer 26 is planarized by a chemical mechanical polishing (CMP) process. There are two cases depending on the degree of planarization.

First, as shown in FIG. 2C, a method of forming a second planarized insulating layer 26a so that the top surfaces of the gate electrodes 23a and 23b are exposed, and as shown in FIG. 2D, the gate electrode 23a ( There is a method of forming the underpolished second insulating layer 26b by leaving a second insulating layer having a thickness of 200 to 800 kPa as in (a) in the upper part of 23b).

In the case of complete polishing as shown in FIG. 2C, when the upper surfaces of the gate electrodes 23a and 23b may be damaged according to the margin of the CMP process, the process proceeds as shown in FIG. 2D. In the case of stabilization, the process proceeds as shown in FIG. 2C.

In the exemplary embodiment of the present invention, the process is performed as shown in FIG. 2D by way of example.

2E, the under-polished second insulating layer 26b over the gate electrodes 23a and 23b is removed by a dry etching or a wet etching process (below the gate upper height). A second insulating layer 26c is formed to expose the top surface of the gate electrodes 13a and 13b.

Here, the thickness to be over etched is 50 to 500 mm 3.

Subsequently, as shown in FIG. 2F, the photoresist 27 is applied to the entire surface and selectively patterned to open only the portion where the n-type impurity ions are to be implanted, and then gate ion implantation is performed using the n-type impurity.

As shown in FIG. 2G, the photoresist 27 is removed and a third insulating layer 28 is formed by depositing a high temperature low pressure deposition (HLD) oxide film of 600 to 800 kPa on the entire surface.

Subsequently, as shown in FIG. 2H, sidewalls of sidewalls of the gate electrodes 23a and 23b of the recessed portions of the second insulating layer 26c which are etched by the third insulating layer 28 by an anisotropic etching process are etched. The mask layer 28a is formed.

As shown in FIG. 2I, the over-etched second insulating layer 26c exposed using the sidewall mask layer 28a as a mask is removed to remove the gate electrodes 23a and 23b below the sidewall mask layer 28a. The second gate sidewall 29 is formed at both sides of the second gate sidewall 29.

Next, as shown in FIG. 2J, an impurity ion implantation process is performed on the entire surface to form the source / drain regions 30 in both substrate surfaces of the gate electrodes 23a and 23b.

As shown in FIG. 2K, the sidewall mask layer 28a is removed by a wet or dry etching process.

Next, as shown in FIG. 2L, the growth of silicon in the active region where the source / drain regions 30 are formed and the upper and upper sides of the gate electrodes 23a and 23b and the adjacent side thereof is 100-800 kPa. The epitaxial growth gate layer 32 is formed to have a thickness.

SEG process conditions are carried out using DCS, SiH ₄ , Si ₂ H ₂ , Si ₂ H ₆ as silicon sources at a temperature of 500-1000 ° C. and a pressure of 1-600 Torr.

As shown in FIG. 2M, the silicide forming metal layer is formed on the entire surface, and the salicide layer 33 is formed on the surface of the selective epitaxial growth gate layer 32 by performing a silicide process by a heat treatment process.

The present invention can reduce the resistance of the salicide layer by expanding the upper portion of the gate electrode to a T-shape by using the SEG process before proceeding to the salicide process.

In addition, in the present invention, an additional ion implantation process is performed after the gate patterning, so that the source / drain ion implantation process is performed independently, and it is natural that such a process may be applied to not only the N gate but also the P gate manufacturing process.

Such a method of manufacturing a semiconductor device according to the present invention has the following effects.

The present invention can reduce the resistance of the salicide layer by enlarging the upper area of the gate electrode by using the SEG process before proceeding to the salicide process, which suppresses salicide agglomeration during the subsequent thermal process and thermally It is effective to secure stability.

In addition, according to the present invention, an additional ion implantation process may be performed after the gate patterning so that source / drain ion implantation processes may be independently performed, thereby easily adjusting the doping profile.

Claims (5)

Forming gate electrodes on the semiconductor substrate; Forming a low concentration impurity region in both substrate surfaces of the gate electrodes, forming first and second insulating layers on the front surface including the gate electrode, and exposing a portion of the upper surface and the upper side surface of the gate electrodes; Optionally masking the gate electrodes and performing a gate ion implantation process in the exposed gate electrodes; Forming a sidewall mask layer on an upper side surface of the gate electrode and removing the first and second gate sidewalls by using the mask to remove the sidewall mask layer; Forming a source / drain region in both substrate surfaces of the gate and forming a selective epitaxial growth gate layer on the exposed substrate surface and the gate electrode surface; Forming a salicide layer on the surface of the selective epitaxial growth gate layer. The semiconductor according to claim 1, wherein the first insulating layer is formed by depositing an HLD oxide film or TEOS at a thickness of 100 to 400 GPa, and the second insulating layer is formed by depositing nitride at a thickness of 2800 to 3200 GPa. Method of manufacturing the device. The method of claim 1, wherein the process of forming the second insulating layer and exposing the upper surface of the gate electrodes is completely planarized by a CMP process to expose the surface of the gate electrodes, or the thickness of 200-800 kPa on the gate electrode. 2. The method of manufacturing a semiconductor device, wherein the second insulating layer is overetched and exposed by an additional etching process after the underpolishing is performed to leave the insulating layer. The method of manufacturing a semiconductor device according to claim 3, wherein the second insulating layer left by the over-etching of the second insulating layer has an upper surface at a position of 50 to 500 Å lower than the surface of the gate electrode. The method of claim 1, wherein the selective epitaxial growth gate layer is subjected to SEG under process conditions using DCS, SiH ₄ , Si ₂ H ₂ , Si ₂ H ₆ as a silicon source at a temperature of 500 to 1000 ° C. and a pressure of 1 to 600 Torr. Proceeding to form a thickness of 100 ~ 800 kHz, the manufacturing method of a semiconductor device.