JPH02272750A - Formation of multilayer wiring and continuous treatment device - Google Patents

Abstract

PURPOSE:To reduce a contact resistance value and to enable formation of a multilayer wiring having good ohmic characteristics by irradiating ultraviolet rays to a bottom of a contact hole which is made in an interlayer insulating film on a semiconductor substrate and by filling it up with a conductive material continuously. CONSTITUTION:When a contact hole 23 is made in an interlayer insulating film 21 on a semiconductor substrate 2, a natural oxidation film 22 is formed slightly on a surface of the substrate 2 of a bottom thereof. The substrate 2 is installed in an ultraviolet ray irradiating device, and ultraviolet rays 24 are irradiated to a bottom of the contact hole 23 in reducing atmosphere. The film 22 is reduced and removed by irradiation of ultraviolet rays 24. The substrate 2 is transferred to a conductive material deposit device without being exposed to atmosphere and a conductive material 25 is filled continuously by selective vapor deposit method to form a multilayer wiring. Accordingly, it is possible to reduce a contact resistance value and to form a multilayer wiring of good ohmic characteristics, thereby improving and stabilizing device characteristics of a semiconductor device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming multilayer wiring in the manufacturing process of semiconductor devices and a continuous processing apparatus.

[Summary of the Invention] The present invention relates to a method and continuous processing apparatus for forming multilayer wiring in the manufacturing process of semiconductor devices, and more specifically, the present invention relates to a method for forming multilayer wiring in the manufacturing process of a semiconductor device and a continuous processing apparatus. The present invention relates to a method of forming a multilayer wiring in which a conductive material is embedded inside the connection, and a continuous processing apparatus for making this method of forming a multilayer wiring possible.

[Conventional technology]

2. Description of the Related Art As semiconductor devices such as LSIs become more highly integrated and operate at higher speeds, the importance of multilayer wiring formation technology is increasing. In particular, the aspect ratio, that is, the ratio of depth to diameter, of connection holes is increasing, for example, to 1 or more, and the importance of reliable embedding techniques for conductive materials into these connection holes is increasing.

Conventionally, selective CVD has been used as a method for embedding a conductive material inside a contact hole opened in an interlayer insulating film on a substrate such as a semiconductor.
, blanket CVD, sputtering, and the like are used. Further, as the conductive material used for embedding, aluminum (AI), its alloy, high melting point metal such as tungsten (W), its silicide, polysilicon (p-3t), etc. are used.

When embedding these conductive materials into connection holes opened in an interlayer insulating film on a semiconductor substrate such as Si, it is extremely important to effectively clean the surface of the substrate exposed at the bottom of the connection hole. The main reason for this is that Si is a substance that is very easily oxidized, so it is difficult to remove the natural oxide film on the surface of the substrate. This is because a new natural oxide film is formed as soon as the substrate is exposed to the atmosphere during this period. If a conductive material is buried inside the connection while the native oxide film is incompletely removed, the contact resistance value may increase or an ohmink contact may not be obtained, which may adversely affect device characteristics. Furthermore, in embedding by selective CVD, self-aligned selective growth may be incomplete, or in some cases, selective growth may not occur at all.

Conventionally, the natural oxide film is removed by performing plasma cleaning with argon (Ar) or the like on the substrate inside a conductive material deposition chamber, or by performing high-temperature, high-vacuum baking, and then continuously conductive Methods of embedding synthetic materials have been used. Furthermore, in the selective CVD method, a conventional technique is known in which the substrate is irradiated with light with a wavelength of 200 to 11,000 nm in a reactive gas atmosphere to form an intermediate product with good adhesion to solve the above problems. (Refer to Japanese Patent Application Laid-Open No. 61-274345).

(Problems to be Solved by the Invention) In the conventional multilayer wiring forming method described above, damage to the substrate due to plasma, contamination from metal in the furnace, or high temperature of 800"C or higher is required. There were problems in practical use.

Further, even if an intermediate product with good adhesion is formed, it is difficult to say that a satisfactory result is necessarily obtained from the viewpoint of removing a natural oxide film.

Therefore, an object of the present invention is to effectively reduce the natural oxide film on the surface of the substrate exposed at the bottom of the connection hole when forming a multilayer wiring by burying a conductive material inside the connection hole opened in an interlayer insulating film on a substrate such as a semiconductor. It is an object of the present invention to provide a method and apparatus for forming a multilayer wiring having low and ohmic contact resistance by removing the conductive material and continuously embedding a conductive material therein. Another object of the present invention is to provide a method and apparatus for forming a multilayer wiring that allows good selective growth when the conductive material is buried by selective CVD.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the multilayer interconnection forming method of the present invention first includes the steps of filling a conductive material into a contact hole opened in an interlayer insulation film on a substrate such as a semiconductor. The method is characterized in that the bottom of the connection hole is irradiated with ultraviolet rays in a reducing atmosphere, and then a conductive material is continuously embedded inside the connection hole. The term continuous, as used herein, means without exposing the substrate to the atmosphere. Also, reducing atmosphere refers to hydrogen (11□) or deuterium (D2) gas, and ultraviolet irradiation refers to 400
It means the irradiation of light with a wavelength of nm or less, regardless of whether it is monochromatic light or continuous spectrum light. The light source is not particularly limited (e.g., a low-pressure mercury lamp, a deuterium lamp, an excimer laser such as ArF, etc.) that has the effect of reducing the natural oxide film on the substrate and that can achieve the purpose of the present invention. The conductive material deposition method for embedding the conductive material inside the contact hole is not particularly limited, and may be selective CVD or blanket CVD.
Furthermore, it is possible to arbitrarily use a method such as sputtering depending on the purpose.

Further, the continuous processing apparatus according to the present invention is an apparatus characterized in that it is equipped with an ultraviolet irradiation device and a conductive material deposition device, which enable the above-described multilayer wiring formation method. Here, the ultraviolet irradiation device has an explosion-proof chamber that has the function of irradiating the substrate with the light source and can use the reducing atmosphere. The conductive material deposition apparatus is not particularly limited, and any apparatus that can achieve the object of the present invention, such as selective CVD, Plunkett CVD, and sputtering, can be used. When the chamber of the ultraviolet irradiation device and the chamber of the conductive material deposition device are provided separately, the two devices may be connected by, for example, a gate valve that allows the substrate to be moved between the devices without being exposed to the atmosphere. Configure. Of course, it is also possible to configure the apparatus so that two chambers serve the functions of both apparatuses.

[Effect]

A natural oxide film formed on the surface of a semiconductor substrate such as silicon exposed at the bottom of a contact hole is reduced and removed by irradiation with ultraviolet rays in a reducing atmosphere as shown in the following equation, so selective CVD is not effective in selective CVD. will be improved, and reliable selective growth will be possible.

SiO□+28z→ Si +2HzO3iO□+H
t→ SiO+ H2O 5tO+ ) 12→ St + HzO At the same time, only the outermost surface of the semiconductor substrate such as silicon exposed at the bottom of the contact hole is heated, and the activation of the dopant proceeds effectively.
In addition to the effect of removing the native oxide film, it becomes possible to create multilayer interconnections with low contact resistance and ohmic contacts.

The multilayer wiring forming apparatus according to the present invention is configured such that the chamber of the ultraviolet irradiation device and the chamber of the conductive material deposition device are connected, for example, by a gate valve, or the both devices are configured integrally, It is possible to deposit a conductive material without exposing a substrate such as a semiconductor to the atmosphere, in other words, without forming a natural oxide film on the surface of the substrate appearing at the bottom of a connection hole.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of a continuous processing apparatus according to a first embodiment of the present invention. In the figure, 1 is an ultraviolet irradiation device, and a semiconductor substrate 2 made of Si or the like is placed on a first susceptor 3 in a chamber of the ultraviolet irradiation device 1. 193 runs of ultraviolet rays from the ArF excimer laser 4 are arranged so as to irradiate the substrate 2 through an ultraviolet irradiation window 5 made of synthetic quartz, for example. 11□ Gas is introduced from the reducing gas introduction hole 6, and the first
The inside of the chamber of the ultraviolet irradiation device 1 is maintained at a reduced pressure and a reducing atmosphere at a constant pressure.

Reference numeral 11 denotes a conductive material deposition apparatus, which in this embodiment is an apparatus for performing selective CVD. The base body 2 is configured to be able to be transferred between apparatuses by a transfer means (not shown), for example, via a gate valve 10 without being exposed to the atmosphere. The substrate 2 transferred from the ultraviolet irradiation device 1 is placed on the second susceptor 12, and the reaction gas introduced from the reaction gas introduction hole 13 is also discharged from the second exhaust hole 14 by a vacuum pump (not shown). The chamber of the conductive material deposition apparatus 11 is evacuated and maintained at a reduced pressure and a constant pressure reaction gas atmosphere.

The base body 2 includes a first susceptor 3 and a second susceptor 12
Using heating means such as a heater inside, it is possible to raise the temperature to an arbitrary temperature as necessary.

In the continuous processing apparatus configured as described above, in this embodiment, a method for forming a multilayer wiring in which connection holes are filled by selective CVD of tungsten (W) will be explained.

FIGS. 3(a) to 3(c) are process diagrams showing a method for forming multilayer wiring according to an embodiment of the present invention. In the figure (a), a connection hole 23 is opened in an insulating film 21 made of 5iOt or the like on a base 2 which is a pSt semiconductor into which boron (B) is implanted as a dopant. Usually, this substrate 2 is hydrogen fluoride (
HF) If the substrate 2 is pretreated with wet etching using water or the like and then cleaned with pure water, or if the substrate 2 is exposed to the atmosphere, a slight natural oxide film will form on the surface of the substrate 2 appearing at the bottom of the connection hole 23. 22 grows. Therefore, this base body 2 is installed on the tenth susceptor 3 of the ultraviolet irradiation device 1, H2 gas is introduced through the reducing gas introduction hole 6, and the gas is depressurized and exhausted through the first exhaust hole 7. The inside of the chamber is maintained in a reducing atmosphere with a reduced pressure of, for example, 10 Torr. Next, 193 by ArF excimer laser 4
The entire surface of the substrate 2 is irradiated with ultraviolet rays 24 of nm wavelength through the ultraviolet irradiation window 5 in a stepwise manner as shown in FIG. 3(b).

The irradiation conditions at this time were pulse energy of 50 mJ/pul.
se, repetition frequency 10Hz, and pulse width 10n3.

By this ultraviolet irradiation, the natural oxide film 22 is reduced and removed, and the temperature of only the outermost surface of the substrate 2 is increased to activate the dopant. The activation rate of the dopant at this time is that the carrier concentration on the surface is 10 g.

013 or more, which is larger than the value obtained by electric furnace annealing at about 900°C,
− barrier height φ for. = 0.67 eV.

Next, the substrate 2 that has been irradiated with ultraviolet rays is transferred into the chamber of the conductive material deposition apparatus 11 via the gate valve 10 without being exposed to the atmosphere, and placed on the second susceptor 12. From the reaction gas introduction hole 13, 10scc+a of tungsten hexafluoride (WF6) and 5scc of silane (SHE) were added.
A mixed gas of 1000 iCC, 1 is introduced into the chamber of 11□, and the pressure is evacuated from the second exhaust hole 14 to maintain the inside of the chamber of the conductive material deposition apparatus 11 at 0.2 Torr. Next, the base body 2 is
Heat to °C. As shown in FIG. 3(c), the electrically conductive material 25 made of - is selectively grown and embedded in the connection hole 23 as described above. By embedding the conductive material 25, it was possible to form a multilayer interconnection with low contact resistance and excellent ohmic properties.

Figure 2 is a schematic sectional view of a continuous processing apparatus according to a second embodiment of the present invention. In the figure, parts having the same functions as those in the first embodiment are given the same names and numbers as those used in FIG. In this embodiment, a case will be described in which the ultraviolet irradiation device 1 and the conductive material deposition device 11 share the same chamber.

15 is a deuterium lamp, which is arranged to irradiate the substrate 2 on the third susceptor 9 with continuous spectrum ultraviolet light having a wavelength of 400 nm or less, for example, through an ultraviolet irradiation window 5 made of synthetic quartz. . The base body 2 is configured to be able to be heated to an arbitrary temperature by, for example, a heater built into the third susceptor 9.

The pressure inside the chamber is controlled by a third vacuum pump (not shown).
The pressure is maintained at a constant value by reducing the pressure through the exhaust hole 8.

In the continuous processing apparatus configured as described above, in this embodiment, a method for forming a multilayer wiring in which connection holes are filled by selective CVD of polysilicon (p-Si) will be explained using FIG. 3 as well.

In FIG. 2A, a connection hole 23 is opened in an insulating film 21 made of SiO□ or the like on a substrate 2 made of a semiconductor such as Si. A small amount of the natural oxide film 22 remains on the surface of the base 2 appearing at the bottom of the connection hole 23. This substrate 2 is placed on a third susceptor 9 in the chamber, and
While raising the temperature to 0°C, deuterium (D2) gas is introduced through the reducing gas introduction hole 6, and the pressure is evacuated through the third exhaust hole 8, so that the inside of the chamber is reduced to a reducing atmosphere of, for example, 50 Torr. keep. Next, the ultraviolet rays 24 of the deuterium lamp 15 are uniformly applied to the entire surface of the base 2 through the ultraviolet irradiation window 5 as shown in FIG.
). The output of the deuterium lamp 15 was, for example, 150W. By this irradiation, deuterium in the chamber is excited, and the natural oxide film 22 on the surface of the base 2 appearing at the bottom of the connection hole 23 is reduced and removed as shown in the following equation.

5i02+20. → Si +2DzO3ing +
02→ SiO+ D, 03iO+ Dz→ Si
+DzO Next, the substrate 2 that has been irradiated with ultraviolet rays is placed on the susceptor 9 in the same chamber, and while maintained at 600°C, for example, 1005 ccra of dichlorosilane (SiH2Ch) and hydrogen chloride ( H
A mixed gas of CI) 10, CI and H210000, C, is introduced and evacuated from the third exhaust hole using a vacuum pump (not shown) to reduce the chamber internal pressure to 100 To
Keep it at rr. As a result of the above, the inside of the connection hole 23 is
), a conductive material 25 made of p-Si was selectively grown in a self-aligned manner and embedded. After this, depending on the purpose, N-type or P-type impurity ions such as boron difluoride ions (BF2'') or phosphorus ions (P'') are implanted, and an activation heat treatment is applied to reduce the contact resistance. , it becomes possible to form multilayer wiring with excellent ohmic properties.

Although a detailed explanation has been given above of the embodiments of the present invention, the gist of the present invention is that when embedding a conductive material into a connection hole opened in an interlayer insulating film on a substrate such as a semiconductor, first a reducing atmosphere is applied. The method is characterized in that the bottom of the connection hole is irradiated with ultraviolet rays, and then a conductive material is continuously embedded inside the connection. Therefore, in addition to the above-mentioned light sources, KrF (2
48nm), an excimer laser using a gas medium such as XeC1 (308ni), a low-pressure mercury lamp, a xenon arc lamp, etc., which irradiates light with a wavelength of 400nm or less, and which exhibits the effects of the present invention, may be used as desired. I can do it.

In addition, as a conductive material deposition apparatus, the above-mentioned selective CVD
The method using a device can improve self-aligned selectivity and is the most effective. However, the present invention is not limited to this apparatus, and a blanket CVD apparatus, a sputtering apparatus, a vapor deposition apparatus, and the like can be used. When using these non-selective deposition devices,
Needless to say, etchback is also used to leave the wiring pattern near the connection hole.

In the two embodiments described above, a heater built into the susceptor was used to raise the temperature of the substrate 2, but this is not particularly limited either, and a halogen lamp, high frequency heating, etc. can be used.

In addition to W and p-3i, the conductive materials to be buried in the connection holes include high-melting point metals such as Mo and aluminum (A
I), A1 alloy, copper (Cu), etc. can be used depending on the purpose, and it is possible to form a multilayer wiring having low and ohmic contact resistance using all of these materials.

〔Effect of the invention〕

As described in detail above, in the method for forming multilayer wiring according to the present invention, when embedding a conductive material inside a contact hole opened in a glabellar insulating film on a substrate such as a semiconductor, first, the bottom of the contact hole is exposed to ultraviolet light in a reducing atmosphere. By applying irradiation and then continuously embedding a conductive material inside the contact hole, it is possible to create multilayer interconnections with low contact resistance (and ohmic contacts), which improves and stabilizes the device characteristics of semiconductor devices. Furthermore, according to the continuous processing apparatus of the present invention, since ultraviolet irradiation and conductive material deposition can be performed continuously, multilayer wiring having the above characteristics can be produced reliably and reproducibly.In particular, If a selective CVD device is used as a conductive material deposition device, the self-aligned selectivity can be improved and the layer effect will be improved. Multi-layer wiring with excellent reliability, which has not yet been achieved in devices, has become possible, and this will greatly contribute to the semiconductor device manufacturing process.

Figures (a) to (c) are process diagrams showing a method for forming multilayer wiring according to an embodiment of the present invention.

1---------・--・-Ultraviolet irradiation device 2・----
---------・--・Substrate 4-----------
--- Eximer laser 5 --- Ultraviolet irradiation window 10 -- Gate valve 11 --- Conductive material deposition device 15 --
・−・−−−−−−−・・−Deuterium lamp 21−・−・
−・−Interlayer insulating film 22・−・−−1−−−−−・−Natural oxide film 23・・−
−11−−−−−−−−Connection hole 24・−・−・−11−−−−Ultraviolet light 25・−・−−・−・−Conductive material

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a continuous processing apparatus according to a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a continuous processing apparatus according to a second embodiment of the present invention, and third FIG. Fig. 1 by carrying out the second embodiment of the present invention Approximate view of the shameful face of Chichirin by continuous processing according to the second embodiment of the present invention A process diagram illustrating a method for forming a forked wire according to an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A method for forming multilayer wiring, which comprises: irradiating the bottom of a contact hole on a substrate with ultraviolet rays in a reducing atmosphere, and then continuously filling the inside of the contact hole with a conductive material. 2. A continuous processing apparatus for carrying out the multilayer interconnection forming method according to claim 1, comprising an ultraviolet irradiation device and a conductive material deposition device.