JPS6240724A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress an increase in a wiring resistance without reducing a film thickness by the pretreatments of steps by eliminating an etching of a TiSi electrode with HF solutions. CONSTITUTION:An SiO2 layer 2 is coated by thermal oxidation as a gate insulat ing layer on a semiconductor substrate 1. Then, an Si layer 3 and a TiSi layer 4 are sequentially coated, and the substrate is then annealed in N2 to form a TiN layer 5. The layers 5, 4, 3 are patterned by anisotropic etching of an RIE method to form gates 5A-3A. The TiSi gate protected by the TiN on the surface is formed by the above steps, an N-type is implanted to the gate in a self-alignment of form an n<+> type source and drain regions 11, 12, thereby forming an essential portion of an FET.

Description

[Detailed description of the invention] [Summary] Titanium silicide (TiS) is used to reduce the wiring resistance of electrodes.
i) When a layer is formed, Ti5iii is easily attacked by hydrofluoric acid (HF) used for pretreatment in various processes, so titanium nitride (TiN) is formed on its surface to remove T from the HF-based liquid.
Protect the iSi layer.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device including an electrode having a TiSi layer.

Due to the demand for higher speed devices, field effect transistors (PETs) are being shifted from polycrystalline silicon (polySt) gates to refractory metal silicide gates in order to reduce delays caused by wiring resistance.

TiSi is advantageous because it has the lowest resistance among silicides, but it is easily attacked by HF-based liquids and the film thickness decreases with each step, so there is a need for countermeasures against this problem.

[Conventional technology]

FIGS. 3(1) and 3(2) are cross-sectional views illustrating the steps of forming a TiSi electrode according to a conventional example.

In this example, a case will be described in which TtSi[ is used for the gate electrode of F'ET.

If a TiSi layer is directly deposited on a silicon (Si) substrate via a silicon dioxide (SiO□) layer as a gate oxide film, the withstand voltage of the gate oxide film will decrease. Ti called
A composite layer of Si/poly-Si is used.

In FIG. 3(1), l is a semiconductor substrate, for example a p-type silicon (St) substrate, on which a silicon dioxide (SiO□) layer 2 is deposited as a gate insulating layer by thermal oxidation.

Next, on the SiO□N2, a poly-Si layer 3 and a TiSi layer 4 are sequentially formed as a gate material by the usual chemical vapor deposition (CVD) method and by sputtering.

Formation of TiSi is performed as follows.

(1) Cospasota using Ti and Si targets separately (a method in which Ti and Si are deposited separately and simultaneously,
The purity of the target is good, but the equipment is complicated and it is not suitable for single wafer type equipment), or the purity of the TiSi alloy target (Ti and Si powders mixed and pressed at high or low temperature) is used. TiS using
Due to sputtering of i. In this case, there is a drawback that the TiSi layer protrudes like an eave due to etching during patterning and the polySi layer is undercut.

(2) Only Ti is deposited on poly-Si by sputtering and formed by a solid phase reaction between Ti and Si by heating.

In Fig. 3 (2), carbon tetrafluoride (CF4) is used as the etching gas, or active ion etching (
Gates (4A, 3A) are formed by patterning the TiSi layer 4 and poly-SiN3 by vertically dominant anisotropic etching using the RIE method.

Through the above steps, a TiSi gate is formed, and after that, the gate is self-lined and n-type impurities are implanted to form an n+
Type source and drain regions 1). 12 and FET
Forms the main part of.

[Problem that the invention seeks to solve]

Conventional TiSi electrodes are easily attacked by liver fluid, and the body
The film thickness gradually decreases due to the SiO□ removal process on poly-Si in a Si multilayer structure, and the pre-treatment process to establish contact between AI and poly-Si, or between poly-Si and poly-Si, and wiring resistance increases. .

Means for Solving Problem C] To solve the above problem, a titanium silicide (TiSi) layer (4) is formed on a semiconductor substrate (1), and the titanium silicide layer (4) is heated in nitrogen. Titanium nitride on the surface (
A method for manufacturing a semiconductor device according to the present invention, comprising forming a TiN layer (5) and patterning the titanium nitride layer (5) and the titanium silicide layer (4) to form electrodes (5A, 4A); A titanium silicide (TiSL) layer (4A) is selectively formed on the electrode formation portion on the semiconductor substrate (1), and titanium nitride (TiN) JLj (5A) is formed on the surface of the titanium silicide layer (4A) by heating in nitrogen. This is achieved by a method of manufacturing a semiconductor device according to the present invention, which includes a step of forming a semiconductor device.

[Effect]

In the present invention, liver fluid easily invades 5iOz and TiSi,
Focusing on the fact that it does not attack TiN, a TiN layer is formed on the TiSi surface by nitrogen (N2) annealing to serve as a protective film against IP-based liquids.

〔Example〕

FIGS. 1(1) and 1(2) are cross-sectional views illustrating the steps of forming a TiSi electrode according to the first invention in order of process.

In this example as well, the gate electrode will be explained in the same manner as in the conventional example shown in FIG.

□1゜301. Hey 7.16, 4□ka. 1) E4) A p-type Si substrate is used, and a SiO□ layer 2 having a thickness of 100 to 300 layers is deposited thereon as a gate insulating layer by thermal oxidation.

Next, on top of the SiO□ layer 2, a thickness of 10
00-3000 poly-Si layer 3, and thickness 1000
~1500 people (7) T i S i layer 4 1) 1)'
rth adhesion.

The steps up to this point are exactly the same as those shown in FIG. 3 of the conventional example.

To form Ti5iJii, Ti is deposited on the entire surface of the substrate and 5
It may be formed by a solid phase reaction between Ti and Si by annealing in argon (Ar) at 00 to 600°C.

Next, the substrate is annealed by heating to 600-900°C in N2, and the surface of the Ti54 layer 4 is coated with a thickness of 100-30°C.
0 TiN layer 5 is formed.

In Fig. 1 (2), I
? The TiN layer 5 is etched by anisotropic etching using the IE method.
Then, the Ti54 layer 4 and the poly-Si layer 3 are patterned to form gates (5A, 4A, 3A).

Through the above steps, a TiSi gate whose surface is protected with TiN is formed, and after that, the gate is self-lined and n
N-type source and drain regions by implanting type impurities 1)
．． 12 to form the main part of the FET.

FIGS. 2(1) and 2(2) are cross-sectional views illustrating the steps of forming a TiSi electrode according to the second invention in order of process.

In this example as well, the gate electrode will be explained in the same manner as in the conventional example shown in FIG.

In FIG. 2 (1), 1 is a semiconductor substrate, for example, a p-type Si substrate, and a gate insulating layer with a thickness of 10 mm is formed on this substrate.
A layer 2 of 0 to 300 Si02 is deposited by thermal oxidation.

Next, on top of the SiO□ layer 2, a thickness of 10
00 to 3000 layers of poly-SiN is deposited and patterned to form a poly-Si layer 3A as an electrode pattern.

Next, Ti is deposited on the entire surface of the substrate and annealed in Ar at 500 to 600° C. to selectively form a TiSi layer 4A only on the poly 51 layer 3A by a solid phase reaction between Ti and Si.

In Figure 2 (2), the substrate was heated to 600 to 900 in N2.
C. for annealing to form a TiNJti5A layer with a thickness of 100 to 300 nm on the surface of the TiSi layer 4A.

Through the above steps, a TiSi gate whose surface is protected with TiN is formed, and after that, the gate is self-lined and n
Type impurities are implanted to form n''' type source and drain regions 1.
). 12 to form the main part of PET.

In the embodiment, an n-type Si substrate was used as the semiconductor substrate, but the gist of the invention does not change even if a p-type Si substrate is used.

Although the embodiments have been described with respect to gate electrodes, the present invention can also be applied to other electrodes or wiring layers.

〔Effect of the invention〕

As explained in detail above, since the TiSi electrode according to the present invention is not attacked by the IIF-based liquid, the film thickness is not reduced by the pretreatment of each step, and therefore, an increase in wiring resistance can be suppressed.

[Brief explanation of the drawing]

FIGS. 1 (1) and (2) are cross-sectional views explaining step-by-step the process of forming a TiSi electrode according to the first invention; FIGS. 2 (1) and (2) are cross-sectional views showing the formation of a TiSi electrode according to the second invention. Cross-sectional views explaining the steps in the order of the steps. FIGS. 3(1) and 3(2) are cross-sectional views explaining the steps of forming the Ti'Si electrode according to the conventional example in the order of the steps. In the figure, 1 is a semiconductor substrate, for example, a p-type Si substrate, 2 is a gate insulating layer, which is an SiO2 layer, 3 is a gate material, which is a poly-Si layer, 4 is a gate material, which is a TiSi layer, and 5 is an HP protective layer, which is a TiN layer layer. Figure 2

Claims (2)

[Claims] (1) Titanium silicide (TiS) is placed on the semiconductor substrate (1).
i) Form a layer (4) and heat it in nitrogen to form a titanium nitride (TiN) layer (5) on the surface of the titanium silicide layer (4).
) and patterning the titanium nitride layer (5) and the titanium silicide layer (4) to form electrodes (5A, 4A). (2) A titanium silicide (TiSi) layer (4A) is selectively formed on the electrode formation part on the semiconductor substrate (1), and a titanium nitride (TiN) layer is formed on the surface of the titanium silicide layer (4A) by heating in nitrogen. A method for manufacturing a semiconductor device, comprising the step of forming (5A).