JPH04105363A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To prevent the fault of an integrated circuit element caused by such a phenomenon that atoms constituting a metal for electrode move to a substrate by forming a insulating barrier film for compensating for the insufficient coating of a barrier metal layer formed in a contact hole on the barrier metal layer at the bottom corner of the contact hole. CONSTITUTION:A silicide layer 6 of, for example, a compound of Pt and Si is formed on the exposing surface of a substrate 3 at the bottom section of a contact hole 5 and a barrier metal layer 7 of TiN, etc., is deposited on the substrate 3. When the barrier metal layer 7 is formed, the layer 7 does not completely cover the substrate 3 at the bottom corner of the contact hole 5. Therefore, a barrier insulating film 8a is only formed in a self-matching way at the corner section where the substrate 3 is not covered completely with the barrier metal layer 7 by deposing an insulating film 8 of SiO2, etc., on the layer 7 and back-etching the entire surface of the film 8 by an anisotropic dry etching method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to semiconductor integrated circuit device technology, and particularly relates to a technology that is effective when applied to a semiconductor integrated circuit device having a Schottky diode (hereinafter referred to as SBD). It is something.

[Conventional technology]

An SBD is a semiconductor device that utilizes the rectifying properties of a Schottky barrier that is formed on a contact surface on the semiconductor side when a predetermined metal and a semiconductor are brought into contact.

FIG. 7 shows a conventional 5BD50. On the upper surface of the semiconductor substrate 51 made of silicon (Si), silicon dioxide (S
An insulating film 52 made of 10□) or the like is deposited. A contact hole 53 is formed in a part of the insulating film 52.

The bottom of the contact hole 53 is made of, for example, platinum (Pt).
A solicide layer 54 made of a compound of and Si is formed. 5BD50 is formed by joining the silicide layer 54 and the semiconductor substrate 51.

Further, in the contact hole 53, a barrier metal layer 55 made of titanium nitride (TiN) or the like and an electrode metal layer 56 made of aluminum (Aβ) or the like are laminated in order from the bottom. The barrier metal layer 55 is an electrode metal layer 56.
It has a function of preventing a phenomenon in which Aβ atoms from entering the semiconductor substrate 51 or, conversely, a phenomenon in which Si atoms in the semiconductor substrate 51 diffuse into the electrode metal layer 55. SBD electrode 5 leading out the electrode from 5BD 50 formed on the semiconductor substrate 51
7 is formed by a barrier metal layer 55 and an electrode metal layer 56.

Regarding the electrode structure formed by the barrier metal layer deposited in the contact hole and the metal layer deposited on the barrier metal layer, for example, see Nikkan Kogyo Shimbun, published September 29, 1986, It is described in rcMoS Device Handbook JP332 to P334.

[Issues that Hathu tries to solve]

However, the present inventors have discovered that the following problems occur in the conventional SBD electrode structure described above.

(1) In recent years, in semiconductor integrated circuit devices, as device dimensions have been reduced, the diameter of contact holes has also been reduced. However, the depth of the contact hole cannot be easily reduced compared to the diameter of the contact hole. This is because there is a limit to reducing the thickness of the insulating film in which the contact hole is formed due to restrictions such as withstand voltage and stray capacitance.

Therefore, the aspect ratio (hole depth/hole diameter) of the contact hole naturally increases as the contact hole diameter becomes finer.

On the other hand, an insulating film in which a contact hole is formed may be formed by stacking insulating film layers with different compositions from the viewpoint of planarization or gettering, or may be formed by stacking insulating film layers of the same composition but manufactured using different methods. There may be cases where In this case, when the contact hole is formed by an etching method or the like, the side wall of the contact hole may take on a reverse tapered shape or a canopy shape due to the difference in the etching speed of each insulating film layer.

However, as described above, when the aspect ratio becomes high or the sidewalls of the contact hole have a reverse tapered shape, the step coverage of the barrier metal layer at the bottom corners and sidewalls of the contact hole is significantly reduced due to the shadowing effect. Therefore, a problem arises in that the A1 atoms constituting the electrode metal layer move to the semiconductor substrate through the insufficient coverage portion of the barrier metal layer, particularly the bottom spacing portion of the barrier metal layer, during heat treatment in the assembly process. Therefore, on a semiconductor substrate, an SBD consisting of PT (silicide layer) and Si (semiconductor substrate) and an A
This creates a situation where a parasitic SBD consisting of I and 81 is formed in parallel, causing a problem in that the work function of the SBD fluctuates and becomes defective.

The second problem will be explained with reference to FIG. FIG. 8 is an enlarged partial cross-sectional view of the bottom corner of the contact hole 53 shown in FIG. Conventionally, as shown in FIG. 8, the end of the insulating film 52 within the contact hole 53 may be displaced in a direction away from the end of the silicide layer 54 by about several tens of micrometers. In this case, the barrier metal layer 56 and the semiconductor substrate 51 come into direct contact with each other to the right of the region A indicated by the broken line in the figure. Therefore, the semiconductor substrate 51
On top, an SBD made of Pt (silicide layer) and Si (semiconductor substrate) and a parasitic SBD made of T1 (barrier metal layer) and Si (semiconductor substrate) are formed in parallel, and 5BD50 The work function of changes,
There was a problem with it becoming defective.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent defects in integrated circuit elements due to the phenomenon in which atoms constituting the electrode metal migrate to the semiconductor substrate through the insufficient coverage portion of the barrier metal layer. The aim is to provide technology that can

Another object of the present invention is to provide a technique that can prevent defects in integrated circuit elements caused by contact between a barrier metal layer and a semiconductor substrate.

The above and other objects and novel features of the present invention will become apparent from the description of the specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the invention according to claim 1 provides a method in which a contact hole reaching an electrode surface of an integrated circuit element formed on the semiconductor substrate is formed in an insulating film deposited on a semiconductor substrate, and a contact hole is formed in an insulating film deposited on a semiconductor substrate, and a layer is coated in the contact hole. A semiconductor integrated circuit device is provided with a lead-out electrode for drawing out an electrode of the integrated circuit element from a barrier metal layer and an electrode metal layer deposited on the barrier metal layer, the lead-out electrode being deposited in the contact hole. This is a semiconductor integrated circuit device structure in which a barrier insulating film is formed at the bottom corner of the barrier metal layer to compensate for insufficient coverage of the 1,1 layer metal layer.

The invention according to claim 2 is characterized in that a contact hole reaching an electrode surface of an integrated circuit element formed on the semiconductor substrate is formed in an insulating film deposited on a semiconductor substrate, and a barrier metal is deposited in the contact hole. A semiconductor integrated circuit device is provided with a lead-out electrode for drawing out an electrode of the integrated circuit element from a metal layer for electrodes deposited on the barrier metal layer and a metal layer for electrodes deposited on the barrier metal layer, wherein a barrier insulating film is provided at a bottom corner of the contact hole. The formed semiconductor integrated circuit device structure is obtained.

[Effect]

According to the above-mentioned invention of claim 1, even if the coverage at the bottom corner of the barrier metal layer in the contact hole is insufficient and a step break or composition abnormality occurs in that part, the barrier insulating film can prevent the insufficient coverage. Therefore, the barrier properties can be maintained regardless of whether the coverage of the barrier metal layer is good or bad.

According to the invention described in claim 2, the barrier properties can be maintained by the barrier insulating film regardless of the coverage of the barrier metal layer in the contact hole. Even if the silicide layer is misaligned in the direction away from the end of the silicide layer, the barrier insulating film can prevent the barrier metal layer from directly contacting the semiconductor substrate.

[Embodiment 1] FIG. 1 is a sectional view of a main part of a semiconductor substrate in a semiconductor integrated circuit device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a part of the semiconductor integrated circuit device, and FIG. Figures (a) to (e)
FIG. 1 is a cross-sectional view of a main part of a semiconductor substrate for explaining a method of manufacturing the semiconductor integrated circuit device.

The semiconductor integrated circuit device of the first embodiment is, for example, a semiconductor memory, and includes a memory cell 1 as shown in FIG.

Memory cell 1 includes a multi-emitter transistor Ql,
It consists of a flip-flop in which resistors R1 and R2 and an SBD (integrated circuit device) 2.2 are connected in parallel to the load of Q2. Word line W, is connected to a load. Further, the word line W2 is connected to the emitter of one of the transistors Q+ and Q2. Also, the data line D is connected to the other emitters of the transistors Q, Q2. 5BD2 is provided to realize high-speed operation in the memory cell 1, and has the role of lowering the impedance of the load.

A cross-sectional view of the semiconductor substrate (hereinafter referred to as the substrate) in the SBD2 portion is shown in FIG. The substrate 3 is made of, for example, Si single crystal. An insulating film 4 made of, for example, 5102 is deposited on the upper surface of the substrate 3.

A contact hole 5 reaching the substrate 3 is formed in a part of the insulating film 4 . The diameter of the contact hole 5 is, for example, about 0.8 to 1 Atm. Further, the depth of the contact hole 5 is, for example, about 1 μm.

A silicide layer 6 is formed at the bottom of the contact hole 5 . The silicide layer 6 is made of, for example, a compound of Pt and S. 5BD2 is formed by joining this silicide N6 and the substrate 3. Note that the portion of the substrate 3 to which the silicide layer 6 is bonded is made of, for example, phosphorus (P).
n-type impurities such as

A barrier metal layer 7 is formed on the silicide layer 6, the side wall of the contact hole 5, and a portion of the insulation wI4. Barrier metal layer 7 is made of, for example, TiN. The thickness of the barrier metal layer 7 is, for example, about 1,000 to 1,500 layers. On the right, the barrier metal layer 7 is not limited to TiN, and can be changed in various ways, for example, TiW.
But it's okay.

By the way, as shown in FIG. 1, the barrier metal layer 7 is
There is a lack of coverage at the bottom corner within contact hole 5. Therefore, in the first embodiment, a barrier insulating film 8a is formed in the portion with insufficient coverage to compensate for the lack of barrier properties of the barrier metal layer 7. Therefore, it is possible to prevent atoms constituting the SBD electrode, which will be described later, from migrating to the substrate 3 through the insufficient coverage portion of the barrier metal layer 7 during heat treatment in the assembly process. The barrier insulating film 8a is, for example, 5102 or a plug?
T E OS (Tetraethoxysilane)
) etc. Note that in FIG. 1, the barrier insulating film 8
Although the barrier insulating film 8 a is also formed on the side wall of the barrier metal layer 7 in the contact hole 5 , the barrier insulating film 8 a does not necessarily have to be formed on the side wall of the barrier metal layer 7 .

An electrode metal layer 9 is formed on the barrier metal layer 7. The electrode metal layer 9 is made of, for example, l, 81, and copper (Cu
). Then, an SB for drawing out the electrode of 5BD2 from the barrier metal layer 7 and the electrode metal layer 9.
A D electrode (extracting electrode) 10 is formed.

Next, a method of manufacturing the semiconductor integrated circuit cover of Example 10 will be explained with reference to FIGS. 3(a) to 3(e).

First, as shown in FIG. 3(a), the contact hole 5
A silicide layer 6 made of, for example, a compound of Pt and Si is formed on the exposed surface of the substrate 3 at the bottom by a normal silicide formation method. That is, the silicide layer 6
and the substrate 3 are bonded to form 5BD2.

Subsequently, as shown in FIG. 3, a barrier metal layer 7 made of TiN or the like is deposited on the substrate 3 by, for example, sputtering. At this time, as shown in the same figure,
Barrier metal layer 7 has insufficient coverage at the bottom corner of contact hole 5 .

Therefore, in the first embodiment, the following processing is performed.

First, as shown in FIG. 3C, an insulating film 8 made of 5x02 or the like is deposited on the barrier metal layer T by, for example, the CVD method.

Next, as shown in FIG. 3(6), the insulating film 8 is etched back by, for example, a full-surface anisotropic dry etching method, and the barrier insulating film 8a is formed in a self-aligned manner only in the insufficient coverage area of the barrier metal layer 7. to form. That is, the lack of barrier properties at the bottom corner of the barrier metal layer 7 in the contact hole 5 is compensated for by the barrier insulating film 8a.

After forming the barrier insulating film 8a, as shown in FIG. 3(e), Aj! is deposited on the barrier metal layer 7 by, for example, sputtering. An electrode metal layer 9 made of a -5i-Cu alloy is deposited. Subsequently, the electrode metal layer 9 and the barrier metal layer 7 are patterned, for example, by an etching method using a photoresist as a mask. As a result, the SBD electrode 10 shown in FIG. 1 is formed.

As described above, according to the first embodiment, it is possible to obtain the following effects.

(1) By forming the barrier insulating film 8a in the insufficient coverage portion at the bottom corner of the barrier metal layer 7 in the contact hole 5, breakage or composition abnormality may occur in the insufficient coverage portion at the bottom corner of the barrier metal layer 7. Even if the coverage is poor, the barrier insulating film 8a compensates for the lack of coverage, so the barrier properties can be maintained regardless of the coverage of the barrier metal layer 7. In addition, during the heat treatment in the assembly process, Al atoms constituting the electrode gold side pass through the insufficient coverage area of the barrier metal layer 7 to the substrate 3.
This makes it possible to prevent the phenomenon of movement. Therefore, it is possible to prevent the work function of 5BD2 from changing due to movement of Al atoms constituting the electrode metal layer 9 to the substrate 3.

As a result, it is possible to prevent defects in the 5BD2, and it is also possible to prevent defects in the memory cell 1 caused by the defects in the 5BD2.

(2) With [1] above, it is possible to improve the reliability of the semiconductor integrated circuit device.

[3) With (1) above, it is possible to improve the assembly yield of semiconductor integrated circuit devices.

[Embodiment 2] FIG. 4 is a sectional view of a main part of a substrate in a semiconductor integrated circuit device according to another embodiment of the present invention, and FIG. 5(a).

5) are sectional views of essential parts of a substrate for explaining a method of manufacturing the semiconductor integrated circuit device shown in FIG. 4.

In the second embodiment, as shown in FIG. 4, a barrier insulating film 8b is also formed on the side wall and bottom corner of the contact hole 5. Therefore, in 5BD2, even if the end of the insulating film 4 in the contact hole 5 is misaligned in the direction away from the end of the solicide layer 6, the barrier metal layer 7 and the substrate 3 are directly connected by the barrier insulating film 8b. It has a non-contact structure. Therefore, it is possible to prevent a phenomenon in which the work function of 5BD2 changes due to contact between barrier metal layer 7 and substrate 3.

The barrier insulating film 8b is, for example, 5102 or plasma TEO.
Consists of 3rd class. Note that the barrier insulating film 8b only needs to be deposited on the bottom corner of the contact hole 5, and does not necessarily need to be deposited on the side wall of the contact hole 5. Also,
A sufficient effect can be obtained by simply forming the barrier insulating film 8b of the two barrier insulating films 3a and 3b shown in FIG.

For example, the barrier insulating film 8b can be formed as follows.

First, as shown in FIG. 5(a), the contact hole 5
After forming a silicide layer 6 on the bottom of the substrate 3, a CV
An insulating film 8 made of SiO□ is deposited by the D method or the like.

Subsequently, the insulating film 8 is etched back by anisotropic dry etching or the like to form a barrier insulating film 8b in the contact hole 5 in a self-aligned manner, as shown in FIGS.

As described above, according to the second embodiment, in addition to the effects obtained in the first embodiment, the following effects can be obtained.

That is, by forming the barrier insulating film 8b also at the bottom corner of the contact hole 5, the barrier metal layer 7 and the substrate 3 do not come into contact at the bottom corner of the contact hole 5, so that the work of 5BD2 due to the contact is reduced. This makes it possible to prevent function fluctuation phenomena. Therefore, due to contact between the barrier metal layer 7 and the substrate 3,
It becomes possible to prevent defects in the BD2.

The invention made by the present inventor has been specifically explained based on Examples above, but the present invention is not limited to Examples 1 and 2, and can be modified in various ways without departing from the gist thereof. Needless to say.

For example, in the first embodiment, the insulating film in which the contact hole is formed is simply 5102, but this insulating film is not limited to a single layer.
It may be a laminated structure of an iO□ film and a silicon nitride (513N4) film, or it may be a laminated structure of insulating films of the same composition formed by different manufacturing methods. In this case, the shape of the contact hole becomes reverse tapered or eave-like,
Although the coverage of the barrier metal layer may be insufficient,
In the present invention, since a barrier insulating film is formed in the insufficient coverage, it is possible to prevent problems such as fluctuations in the work function of the SBD caused by insufficient coverage.

Furthermore, in Example 1.2, the case where the barrier insulating film was formed by an anisotropic dry etching method was explained, but the invention is not limited to this. For example, as shown in FIG. A barrier insulating film 8C can also be formed at the bottom corner on the barrier metal layer by photolithography.

The above explanation will mainly focus on the SB of semiconductor memory, which is the application field that was the background of the invention made by the present inventor.
Although the case where the present invention is applied to the D portion has been described, the present invention is not limited thereto and can be applied in various ways, and can also be applied to other integrated circuit element portions of other semiconductor integrated circuit devices.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

(1), that is, according to the invention set forth in claim 1, even if coverage at the bottom corner of the barrier metal layer in the contact hole is insufficient and breakage or composition abnormality occurs in that part, the barrier insulating film can prevent the problem from occurring. Since the lack of coverage is compensated for, the barrier properties can be maintained regardless of the quality of the coverage of the barrier metal layer. Therefore, it is possible to prevent atoms constituting the electrode metal layer from migrating to the substrate through the insufficient coverage portion of the barrier metal layer during heat treatment in the assembly process. therefore,
For example, it is possible to prevent variations in the work function of the SBD due to the movement of atoms constituting the electrode metal layer to the substrate, thereby making it possible to prevent defects.

(2) According to the invention set forth in claim 2, the barrier property can be maintained by the barrier insulating film regardless of the coverage of the barrier metal layer in the contact hole, and, for example, the edge of the insulating film in the contact hole Even if the barrier metal layer and the substrate are displaced in the direction away from the # part of the silicide layer constituting the SBD, the barrier metal layer and the substrate do not come into direct contact with each other due to the barrier insulating film, so the work function of the SBD due to the contact between the barrier metal layer and the substrate It is possible to prevent fluctuations in the temperature and prevent defects thereof.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a substrate in a semiconductor integrated circuit device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a part of the semiconductor integrated circuit device, and FIGS. 3(a) to (e) ) is a cross-sectional view of a main part of a substrate in a semiconductor integrated circuit device according to another embodiment of the present invention, and FIG. Figures (a) and (b) are sectional views of essential parts of a substrate for explaining the manufacturing method of the semiconductor integrated circuit device shown in Figure 4, and Figure 6 is a semiconductor integrated circuit according to another embodiment of the present invention. FIG. 7 is a partial sectional view of a conventional SBD. FIG. 8 is an enlarged partial sectional view of the substrate showing the bottom corner of a contact hole in a conventional SBD. 1...Memory cell, 2...5BD (integrated circuit element)
, 3... Substrate, 4... Insulating film, 5... Contact hole, 6... Silicide layer, 7... Barrier metal layer, 8... Insulating film, 8a to 8C... Barrier insulation film,
9...Metal layer for electrode, 10...SBD electrode (lead electrode), Ql, Q2...Transistor, R,
, R,...Resistance, W,, W2... Word line, D...
...Data line, 50...SBD, 51...Substrate, 5
2... Insulating film, 53... Contact hole, 54...
...Silicide layer, 55...Barrier metal layer, 56.
...metal layer for electrode, 57...SBD electrode, A...area. Figure 1 4-2 6 8a Figure 3 Figure 3 Figure 3 Figure 4 Figure 4 Figure 5 8b 8b: Barrier insulating film Figure 5. Figure 6 n to 1

Claims (1)

[Claims] 1. A contact hole reaching an electrode surface of an integrated circuit element formed on the semiconductor substrate is formed in an insulating film deposited on a semiconductor substrate, and a barrier metal is deposited in the contact hole. A semiconductor integrated circuit device comprising an extraction electrode for drawing out an electrode of the integrated circuit element from a layer and an electrode metal layer deposited on the barrier metal layer, the barrier metal layer deposited in the contact hole. A semiconductor integrated circuit device characterized in that a barrier insulating film is formed at an upper bottom corner to compensate for insufficient coverage of a barrier metal layer. 2. A contact hole reaching the electrode surface of an integrated circuit element formed on the semiconductor substrate is formed in the insulating film deposited on the semiconductor substrate, and a barrier metal layer deposited in the contact hole and on the barrier metal layer are formed. A semiconductor integrated circuit device is provided with a lead-out electrode for drawing out an electrode of the integrated circuit element from a metal layer for electrodes deposited on the semiconductor integrated circuit device, characterized in that a barrier insulating film is formed at a bottom corner of the contact hole. Semiconductor integrated circuit device. 3. A semiconductor integrated circuit device, further comprising a barrier insulating film formed at a bottom corner of the barrier metal layer deposited in the contact hole according to claim 2, to compensate for insufficient coverage of the barrier metal layer.