JPH04323872A - Material for semiconductor device - Google Patents

Abstract

PURPOSE:To cope with an increase in an address wiring of a thin film transistor(TFT) by forming of an Al-based alloy containing a specific amount of one or more types of Mn, Cr, Zr as alloy components. CONSTITUTION:A material for a semiconductor device is formed of an Al-based alloy containing total amount of 0.05-1.0 atomic % of one or more types of Mn, Cr, Zr as alloy components. The material formed of the Al-based alloy can be formed by a sputtering method, and as a sputtering gate of the case, it is desirable to use an Al-based alloy manufactured by a melting and casting method or a powder baking method. This melted Al alloy target is homogeneous in composition, and uniform in its sputtering rate and its emitting angle. Thus, the material can cope with narrowing of a wiring width upon high integration of the device, or an increase in a wiring length of a TFT upon increase in a screen and size of a liquid crystal display.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to semiconductor device materials, and more particularly to thin film Al-based wiring or electrode materials for semiconductor devices, particularly thin film transistors used in liquid crystal displays and the like.
The present invention relates to a semiconductor device material suitable for use in nsister (hereinafter referred to as TFT).

0002

[Prior Art] Thin film Al-based metal materials are used as electrodes and wiring materials for integrated circuits in general semiconductor devices (that is, semiconductor devices in which elements are formed on a Si wafer). There are Al and Al-based alloys containing Si, Cu, or Mg.

Pure Al is the best in terms of low electrical resistance and good adhesion, but it has a low melting point, poor heat resistance, and stress migration (hereinafter referred to as SM).
There are problems such as electromigration (hereinafter referred to as EM) and electromigration (hereinafter referred to as EM). Here, SM refers to bulges (hillocks) and disconnections (defective conduction) of thin film wiring caused by stress, and is mainly caused by heating. EM is a disconnection of thin film wiring caused by electrophoresis, and is mainly caused by energization.

[0004]Al-based alloys containing Si, Cu or Mg were developed to improve the above problems, but
From the perspective of suppressing the increase in specific resistance, the amount of alloying elements added is 2 at% or less, which improves SM resistance and E resistance.
M property is still not sufficient. Also, although its corrosion resistance is superior to pure Al, it is still insufficient in terms of long-term reliability. Therefore, there is a demand for the development of new semiconductor device materials with higher reliability.

[0005]Although further alloying may be considered,
The resistance value of metals generally tends to increase due to alloying, but on the other hand, due to the miniaturization of interconnects (narrower interconnect widths) associated with the high integration of semiconductor devices in recent years, the allowable upper limit of electrical resistance value has become lower. Therefore, simply alloying exceeds the upper limit, and it is therefore not easy to develop new semiconductor device materials.

[0006] Unlike the general semiconductor devices mentioned above, the electrode and wiring materials for TFTs are heated to a relatively high temperature (about 400°C or lower) during the TFT manufacturing process, so Al-based metal materials are used. However, metal materials with high melting points such as Ti, Cr, Mo, and Ta are often used because they produce SM and lack heat resistance. However, these have the problem of high electrical resistance, and an improvement is desired.

Furthermore, in recent years, liquid crystal displays have become larger and have larger screens, and the wiring (address wiring) connecting each TFT element has also tended to increase in length.As a result, resistance and capacitance increase, resulting in a delay in the address pulse. This makes it difficult to use the above-mentioned high-melting-point metal materials.Therefore, it is desired to develop a new heat-resistant metal material with low wiring resistance.

The electrical resistance required for such TFT wiring is approximately 30 μΩcm or less, and in order to further expand its use, it is desired that it be at the same level as conventional Al-based alloys (10 μΩcm or less). Metal species that meet this requirement include Au and C.
There is u, Al, but it is difficult to use Au because it is expensive.
Cu has problems in terms of adhesion and acid resistance, and Al is a low melting point metal and lacks heat resistance and may cause interlayer (line) short circuits due to SM, so neither of them can be put to practical use.

[0009] Therefore, multilayer wiring (composite wiring), alloying of the wiring surface portion by ion implantation (surface alloyed wiring), etc. have been proposed. In this multilayer wiring, the lower layer is made of a low resistance material and the upper layer is made of a high heat resistant material.
It is designed to demonstrate the multiple functions of The surface alloyed wiring is made by ion-implanting a different element into a low-resistance material to provide a heat-resistant alloy layer on the surface, and exhibits the same function as described above.

However, in manufacturing multilayer wiring, it is necessary to perform film formation twice, and depending on the combination of lower and upper layers, etching for forming the wiring pattern must be performed in a separate process, which increases the number of processes. Surface alloyed wiring requires a complicated process of ion implantation, and it is difficult to control the surface alloy layer, resulting in an increase in processes and a decrease in production yield. Therefore, there is a current demand for the development of a new metal material for TFTs that does not have such problems, has low wiring resistance, and has excellent heat resistance.

[0011]

[Problems to be Solved by the Invention] The present invention has been made paying attention to the above-mentioned circumstances, and its purpose is to solve the above-mentioned problems of the conventional products, and to improve heat resistance (SM resistance).
It has excellent EM resistance and corrosion resistance, and has a low electrical resistance of 10 μΩcm or less, making it suitable for general semiconductor devices and TF.
It can be suitably used for T without causing a decrease in productivity, and it can also be used as a TF due to the narrowing of wiring width due to the high integration of semiconductor devices in recent years and the increase in the screen size and size of liquid crystal displays.
Semiconductor device material (
The aim is to provide electrode/wiring materials).

0012

Means for Solving the Problems In order to achieve the above object, the present invention provides a semiconductor device material having the following configuration. That is, the semiconductor device material according to the present invention is characterized by being made of an Al-based alloy containing one or more of Mn, Cr, and Zr as alloy components in a total amount of 0.05 to 1.0 at%. It is a material for semiconductor devices.

[0013]

[Operation] The present invention manufactures targets made of Al-based alloys with various compositions, forms Al-based alloy thin films for semiconductor device wiring by sputtering, and adjusts the composition, heat resistance (SM resistance) of these Al-based alloy thin films. This is based on the following knowledge obtained as a result of investigation of EM resistance, corrosion resistance, and electrical resistance.

That is, A containing one or more of Mn, Cr, and Zr (hereinafter referred to as Mn, etc.) as an alloy component.
It has been found that l-based alloy thin films have the best heat resistance (SM resistance, etc.) and are effective with the addition of very small amounts of alloy components, and also have excellent EM resistance and corrosion resistance, as well as low electrical resistance. It was done. In detail, heat resistance and EM resistance are superior to conventional Al-based alloys, and Ti, Cr, Mo,
It has been found that it can be made to the same level as or higher than high melting point metal materials such as Ta, corrosion resistance can be improved compared to conventional Al-based alloys, and electrical resistance can be made to be 10 μΩcm or less.

[0015] At this time, the total content of Mn etc. is 0.0
It is necessary to make it 5 at% or more, and 0.05 at%
If it is less than that, the heat resistance and corrosion resistance will be insufficient, which is not good. Heat resistance improves as this content increases, but 1.0
If it exceeds at%, the electrical resistance becomes larger than 10 μΩcm and does not satisfy the target value of electrical resistance according to the present invention. Therefore, the content of Mn and the like (one or more of Mn, Cr, and Zr) needs to be 0.05 to 1.0 at%.

Since the Al-based alloy thin film described above can be produced by the same method as conventional Al-based metal alloy thin films, it does not cause a decrease in productivity as in composite wiring or surface alloyed wiring by ion implantation.

Therefore, the semiconductor device material according to the present invention is
As mentioned above, one of Mn, Cr, and Zr is used as an alloy component.
It is made of an Al-based alloy containing a total of 0.05 to 1.0 at% of two or more species, and therefore, based on the above knowledge, it has excellent heat resistance (SM resistance, etc.), EM resistance, and It has excellent corrosion resistance and has a low electrical resistance of 10 μΩcm or less, so it can be used suitably for general semiconductor devices and TFTs without causing a decrease in productivity, and moreover, it can be used for wiring widths that have become narrower due to the recent increase in the degree of integration of semiconductor devices. In addition, it may be possible to cope with the increase in the number of TFT address wirings accompanying the increase in screen size and size of liquid crystal displays.

The semiconductor device material made of the Al-based alloy according to the present invention can be formed by a sputtering method, and the sputtering target used in this case is an Al-based alloy (hereinafter, an Al-based alloy manufactured by a melting/casting method or a powder sintering method). It is preferable to use an aluminum alloy target. Since such a melted Al alloy target is uniform in composition, and has a uniform sputtering rate and emission angle, an Al-based alloy film (i.e., wiring/electrode material) can be obtained, and therefore, it can be used with higher reliability. It becomes possible to manufacture semiconductor devices. Among them,
The target manufactured by the melting/casting method has an oxygen content of 10
0 ppm or less, which makes it easier to maintain a constant film formation rate and lowers the amount of oxygen in the Al-based alloy film.
Therefore, it becomes easier to reduce the electrical resistance and improve the corrosion resistance of the Al-based alloy film.

[0019]

【Example】

(Example 1) Ta was deposited on a soda lime glass substrate to a thickness of 5000 Å by DC magnetron sputtering.
After forming the 2O5 film, an Al alloy film with a thickness of 3000 Å was formed on the Ta2O5 film by the same method as above using melted Al alloy targets having various contents of Mn, Cr, and Zr. The Al alloy film was processed into a 10 μm wide stripe pattern by photolithography and wet etching, and used as a sample. Further, as a comparative example, a sample in which a Ti film was formed in place of the Mn, Cr, and Zr was processed in the same manner as above and used as a sample.

The above sample was subjected to vacuum heat treatment at 400° C. for 1 hour, and then the number of hillocks generated on the surface of the stripe pattern was measured to determine the hillock density. The results are shown in Figure 1. Hillock density decreases with the addition of Ti, Mn, Cr, and Zr, but the degree of decrease is dependent on T.
It can be seen that this is more remarkable in the case of addition of Mn, Cr, and Zr than in the case of i. Furthermore, it can be seen that the addition of Mn, Cr, and Zr significantly reduces the hillock density and improves the SM resistance even when added in small amounts compared to the case of adding Ti. The effects of adding Mn, Cr, and Zr are independent, and additivity holds for the decrease in hillock density. Therefore, this effect holds even when Ti and Ta are added simultaneously.

(Example 2) After forming an Al alloy film with a thickness of 2000 Å on a soda lime glass substrate by the same sputtering method using the same target as in Example 1, the aluminum alloy film was formed by the same method. Membrane width: 100μm,
A striped sample with a length of 10 mm was processed. Next, the specific resistance of the sample was measured by the four-probe method. The results are shown in FIG. The specific resistance increases as the amounts of Mn, Cr, and Zr increase. It is desirable that the specific resistance is as low as possible, and the upper limit of the specific resistance varies depending on the type of semiconductor device to which it is applied, but as an electrode/wiring material for TFTs for liquid crystal displays, it is at the same level as conventional Al-based alloys (approximately 10 μΩcm).
), and in order to secure this value, Mn, Cr, Zr
It can be seen that the amount should be 1 at% or less. Above 10μ
Ωcm is the specific resistance (5
0 μΩcm or more), and corresponds to about 1/5 of that. Therefore, the semiconductor device material of the present invention can sufficiently cope with the increase in the number of TFT address wirings accompanying the increase in screen size and size of liquid crystal displays. It is clear that it can be used with advantage.

[0022]

Effects of the Invention The semiconductor device material according to the present invention has the structure and function as described above, and has excellent heat resistance (S resistance).
It has excellent EM resistance and corrosion resistance, and has a low electrical resistance of 10 μΩcm or less, so it can be suitably used for general semiconductor devices and TFTs without causing a decrease in productivity. This has the effect of being able to sufficiently cope with the narrowing of wiring widths accompanying higher integration of devices and the increase in the number of TFT address wirings accompanying larger screens and larger liquid crystal displays.

[Brief explanation of the drawing]

FIG. 1: Each element (
FIG. 3 is a diagram showing the relationship between the content (Mn, Cr, Zr, or Ti) and hillock density.

FIG. 2 is a diagram showing the relationship between the content of each element (Mn, Cr, Zr) and specific resistance for the Al alloy thin film according to Example 2.

Claims (1)

[Claims] Claim 1: One or more of Mn, Cr, and Zr as alloy components in a total amount of 0.05 to 1.0 at%.
A semiconductor device material comprising an Al-based alloy containing Al.