JPH0682666B2 - Electronic device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sensor using an aluminum film or an aluminum alloy film as a wiring material, a memory, a semiconductor integrated circuit for performing information processing, an electronic device such as an optoelectronic device, and the like. Regarding improvement.

(Problems to be solved with conventional technology) In many conventional electronic devices, an aluminum film manufactured by a vacuum deposition method or a sputtering method is used as a wiring material for patterning because of its low specific resistance and good stability. I am using it. However, when the aluminum film produced by the above method is used as a wiring material for a silicon semiconductor device, the interdiffusion between silicon and aluminum on the substrate becomes large, and the stability at the contact portion deteriorates (this is called penetration). Since migration and stress migration occur, an aluminum silicon alloy film is used as a wiring material in order to prevent this.

Here, the aluminum-silicon alloy includes a film in which silicon is segregated between the aluminum-silicon grains.

For example, FIG. 4 shows a conventional N-type silicon
It is a structure diagram of a gate MOS (Metal Oxide Semiconductor).

11 is a P-type silicon substrate doped with boron, 12 is a silicon oxide film grown by exposing the substrate 11 to a high temperature atmosphere, and 13 is a pattern of the silicon oxide film 12, and phosphorus is ion-implanted into the portion. layer, N by the CVD method is 14 ^{- -} and N formed by the silicon oxide film grown on the layer 13, 15 after patterning the silicon oxide film 14, a gate oxide grown by exposure to a high-temperature oxygen atmosphere Film, 16 is a polysilicon gate layer grown on the gate oxide film 15, and 17 is the substrate 11.
An aluminum film or aluminum silicon alloy film (hereinafter referred to as an aluminum film) as a wiring material formed on the entire surface by a vapor deposition method, a sputtering method, a thermal CVD method, etc., 18 is a CVD method for lowering the surface reflectance of the aluminum film 17 etc. Alternatively, a silicon tungsten film formed by a sputtering method, and 19 is a passivation film of silicon nitride or the like.

Aluminum film or the like 17 formed by vapor deposition or sputtering as the wiring material of the semiconductor device having the above-described structure
The film thickness of is usually about 1 μm as the film thickness of the wiring material of the electronic device, but the grain 20 of about 1.5 μm is formed as shown in FIG. When such grains 20 are formed, electromigration occurs from the joints between the grains 20, which changes the characteristics of the electronic device, and in some cases causes disconnection or short circuit of the wiring. Furthermore, hillocks (hill-shaped protrusions) may be formed on the aluminum wiring due to the annealing required in the subsequent process.

Therefore, in recent years, it has been attempted to add copper to this aluminum-silicon alloy and improve the characteristics of the joint by segregating the copper in the joint of the grain to prevent the occurrence of electromigration and stress migration. Has been. However, when copper is added as described above, copper remains as an etching residue when dry etching is performed for patterning the aluminum-silicon-copper alloy film.

Therefore, ion sputter etching can be used together to remove the copper, but this may damage the resist or change the device characteristics due to high-energy ion irradiation.

On the other hand, attempts have been made to reduce the grain size,
If nitrogen is introduced during the sputtering, the grain size will be about 0.5 μm, which can be made slightly smaller than that of the conventional one. However, there is a strong possibility that the above-mentioned nitrogen will be mixed into the film, and it cannot be essentially improved.

The growth of the aluminum film 17 by thermal CVD is introduced in the following document.

(1) “LPCVD ALUMINUM FOR VLSI PROCESSING” RA Revy and MLGreen J. Electrochem. Soc.134 (1987) P37c (2) “LPCV of Aluminum and Al-Si Alloys for Semi
conductor metallization "MJCooke RAHeinecke RCSten Solid State Techno
logy December1982 P62-65 Both of the thermal CVD methods shown in the above references (1) and (2) use the same hot wall type CVD apparatus. That is, the substrates are arranged in the reaction chamber of the quartz glass tube, and the process gas for heating the substrate from the outside of the quartz glass tube by the furnace is flowing in the axial direction of the quartz glass tube.

When an aluminum film is produced by this, the step coverage is improved, but since the produced film surface is rough (reflectance: about 10 to 20%), the bondability between grains is poor and electromigration and stress migration occur. Resulting in.

Furthermore, the cluster ion beam vapor deposition method and the magnetron plasma CVD method, which are introduced in the following documents, are known as those capable of producing an aluminum film having a good surface flatness.

That is, (3) "Al film formation and crystallinity control by ICB method" Yamada, Takagi Monthly Semiconductor World (Japanese version) March issue (1987) P75 The method shown in the document is a crucible containing aluminum. Are heated to generate clusters in a high vacuum, the cluster beams are ionized by electron impact, and the substrates are irradiated as ion cluster beams to form a film.

However, as shown in the cross-sectional view of FIG. 6, the aluminum film manufactured by this method has a poor coverage of the step portion 21 and may be broken, so that it cannot be used for wiring of an electronic device.

(4) "Formation of Al film by MPCVD" Kato, Ito Monthly Semiconductor World (Japanese version) March issue (1987) P84 The method shown in the document is the N pole, S pole on the back surface of the substrate holder at the ground potential. The magnet of the pole is grounded in a rotated state, and high-frequency power is applied to the gas blowing portion at a position facing the substrate to perform magnetron plasma CVD.

According to this method, carbon is mixed in the formed aluminum film in the order of several%, and the specific resistance is 4 to 10 μm.
Large as Ω · cm. For this reason, the low specific resistance (2.7 μΩ · cm), which is the original feature of aluminum wiring, cannot be effectively used, and it is not suitable as a wiring material.

(Object of the Present Invention) The object of the present invention is to reduce electromigration and stress migration by using an aluminum film or the like having less grain, excellent surface flatness, and excellent step coverage as a wiring material of an electronic device. Another object of the present invention is to provide a stable electronic device by preventing the generation of hillocks.

(Means for Solving Problems) The present invention is configured as follows to achieve the above object. That is, in an electronic device having a wiring material made of an aluminum film or an aluminum alloy film,
The aluminum film or aluminum alloy film first heats a predetermined gas to first generate the first step of the thermal CVD reaction, and then supplies this gas to the surface of the substrate, and the first of the thermal CVD reaction on the surface of the heated substrate is performed. The film is characterized by being a film formed by a thermal CVD method so that the film is formed on the surface of the substrate in the two steps.

(Example) FIG. 1 shows a state of an aluminum film or the like produced as a wiring material of an electronic device according to the present invention.
The figure is a cross-sectional view showing the step coverage property of an aluminum film or the like, and FIG. 3 is a front cross-sectional view of a thermal CVD apparatus used for producing the aluminum film or the like.

The structure of the electronic device according to this embodiment is the same as that of the conventional device shown in FIG. Further, the same reference numerals are used for the same constituent elements as in FIG.

As shown in FIG. 1, an aluminum film 17 having good flatness is formed on the silicon substrate 11. In order to produce this aluminum film etc. 17, the thermal CVD apparatus shown in FIG. 3 is used.

Reference numeral 1 is a processing chamber, which has a structure that can be kept airtight. Reference numeral 3 denotes a substrate holder which is disposed in the processing chamber 1 to hold the substrate 11 and adjust the temperature of the substrate 11.

Explaining the configuration of the temperature adjusting mechanism for adjusting the temperature of the substrate holder 3, 4 is a heater for heating the gas holder 3 by resistance heating (this may be another heating method such as radiant heating), A thermocouple 5 monitors the temperature of the substrate holder 3. A temperature measuring resistor may be used instead of the thermocouple 5 as the temperature monitor. Thermocouple 5
The signals measured at are PID control, PI control, ON-
It is input to a control circuit such as OFF control, and the input power of the heater 4 is adjusted by using a thyristor or a relay to adjust the temperature of the substrate holder 3. When necessary, the substrate holder 3 can be cooled and the temperature is adjusted by both heating and cooling methods.

A predetermined gas 8 is introduced into the processing chamber 1 through a valve 7 from a gas supply device (not shown). In order to supply the gas 8 to the gas surface with good uniformity, a large number of gas passages such as multiple meshes A distribution plate 31 having blowout pores is provided. A temperature adjusting mechanism 40 is incorporated in the distribution plate 31.

The temperature adjusting mechanism 40 is a heating means 41 provided on the distribution plate 31,
The temperature monitor 42 and feedback control means (not shown) are mainly configured, and the heating means 41 is a distribution plate.
The heater 31 is heated by resistance heating from the atmospheric pressure side by the heater 32. The effect is the same when radiant heating is performed with a halogen lamp or the like instead of resistance heating. The heater 32 is insulated from the distribution plate 31 by using an insulating powder 34. The insulating powder 34 may be alumina or the like, but it is better to use magnesia powder in consideration of the conductivity of heat from the heater.

Further, although the feedback control means is not shown, the signals obtained by measuring with the thermocouple 33 are PID control, PI control, ON-OFF
It is fed back to a control circuit such as control, and the input power of the heater 32 is adjusted by using a thyristor or a relay, and the distribution plate 31
It adopts a configuration to control the temperature of.

Reference numeral 35 is a lid for fixing the insulating powder 34.

To produce the aluminum film or the like 17 as a wiring material using the apparatus having the above-mentioned configuration, as an example, it is performed under the following film forming conditions.

The pressure in the processing chamber 1 was set to 2 Torr, triisobutylaluminum was used as the introduction gas, and argon (flow rate 50 to 200 sccm) was used as the carrier gas.
The distribution plate 31 is set to 0 ° C. and 230 ° C. to give “first step of thermal CVD reaction” to triisobutylaluminum, and then supplied to the surface of the substrate 11 heated to 350 to 400 ° C. To do. As a result, the "second stage of the thermal CVD reaction" occurs on the surface of the substrate 11 and the aluminum film 17, etc. is exposed to 1 μm / mi.
A film can be formed on the substrate 11 at a rate of n. The film 17
Conventional example (1) relating to the thermal CVD described above for the surface of
Compared to (2), it is very flat.

That is, the surface reflectance of the films produced by the conventional examples (1) and (2) is about 10 to 20%, which is a rough surface having very unevenness by SEM observation. On the other hand, the aluminum film or the like according to the present invention has a light reflectance of 220 to 8000 nm and a surface reflectance of 95% or more at a film thickness of 1 μm. This has better flatness than the case of a film formed by a conventional sputtering method.

Also, as shown in FIG. 1, the aluminum film or the like 17 formed on the substrate 11 is different from the sputtered film in the SEM observation, and a film such that the grain 20 as shown in FIG. 5 cannot be confirmed is obtained. You can

In addition, when the film is formed under the above film forming conditions, Si (crystal orientation 111
Epitaxial growth of A1 (crystal orientation 111 plane) is possible on (plane) substrate and streak pattern can be obtained by RHEED. Alternatively, epitaxial growth of Al-Si (100 crystal planes) is possible on a Si (100 crystal planes) substrate.

Further, as shown in FIG. 2, as compared with the case of FIG. 6 in which the film was formed by the cluster ion beam vapor deposition method, the coverage at the step portion 21 was remarkably improved, and the possibility of disconnection disappeared.

Further, by controlling the parameters with respect to the specific resistance of the film by using the above-mentioned device, the specific resistance of 2.7 μΩ · cm can be easily obtained even at the film thickness of 1 μm with good flatness. In addition, the amount of carbon is small and is less than about 20 ppm. When this film was annealed at 430 ° C. for 40 minutes in N ₂ atmosphere, no hillock was observed. This is a very excellent feature as compared with the film formed by the sputtering method.

The aluminum film or the like produced by the above apparatus has good flatness, little impurities mixed therein, and excellent step coverage and crystallinity, and is optimal as a wiring material for electronic devices.

When manufacturing an electronic device, after forming an aluminum film or the like as a wiring material of the device by the above method,
This is etched and patterned, and a tungsten silicon film 18 is formed on the film by a CVD method or a sputtering method as in the case of a normal aluminum material for wiring.
Å Film is formed. This is done to reduce the surface reflectance so that exposure and patterning will not be impossible due to the high reflectance of the aluminum film or the like.

Although the semiconductor device using the aluminum film or the like as the wiring member has been described in the above embodiments, the present invention is not necessarily limited to this and widely includes other electronic devices such as an optoelectronic device.

(Effect of the invention) According to the claims, by using an aluminum film or the like produced by a predetermined thermal CVD method for the wiring of the electronic device, electromigration, stress migration and hillock do not occur in the device.

[Brief description of drawings]

FIG. 1 is a partial perspective view of an aluminum film or the like produced as a wiring material of an electronic device according to the present invention, and FIG. 2 is a sectional view showing step coverage of an aluminum film or the like produced by a thermal CVD method. FIG. 3 is a front sectional view of a CVD apparatus used for producing an aluminum film, etc., FIG. 4 is a structural diagram of a conventionally known N-type silicon gate MOS, and FIG. 5 is produced by a sputtering method. FIG. 6 is a partial perspective view of the aluminum film, and FIG. 6 is a cross-sectional view showing the step coverage of the aluminum film produced by the cluster ion beam deposition method. 11 …… Substrate, 12 …… Silicon oxide film, 13 …… N ⁺ , 17 ……
Aluminum film or aluminum-silicon alloy film.

Claims (1)

[Claims] 1. An electronic device having a wiring material made of an aluminum film or an aluminum alloy film, wherein the aluminum film or the aluminum alloy film heats a predetermined gas to first cause a first stage of a thermal CVD reaction. The film is produced by a thermal CVD method in which this gas is supplied to the surface of the substrate later and the film is formed on the surface of the substrate by the second stage of the thermal CVD reaction on the surface of the heated substrate. Electronic device.