JP2544185B2 - Thin film forming apparatus and method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus and method for selectively forming a thin film on a desired portion of a substrate.

(Prior Art) As the degree of integration of semiconductor devices has increased and the patterns have become finer, embedding technologies such as selective growth technology and planarization technology have become important.

A conventional completed selective growth technique is a selective tungsten growth method. Using this method, for example, as shown in FIG. 4a, which is an enlarged sectional view of the film deposition process on the surface of the substrate (left figure → right figure), the patterned silicon dioxide film 220 on the substrate 2'of silicon 100 is formed. Tungsten 310 can be selectively formed only in the recessed portion 222 between and the filling can be performed. However, as the degree of integration of semiconductors increases, the specific resistance of metals becomes a problem, and there is an increasing demand for embedding with a metal having a specific resistance smaller than that of tungsten.

By the way, there is a report that a thin film is selectively formed only on the concave portion of aluminum having a small specific resistance.

Takao Amazawa et al. Selectively produce an aluminum film by a low pressure CVD method using triisobutylaluminum as a raw material. (Extended Abstr acts of the 18th Co
nference on Solid State Devices and Materials, Toky
o, 1986, pp755-756).

FIG. 4b shows an enlarged sectional view of the surface of the substrate similar to that in the selective tungsten growth method. As is clear from this figure, in this document, the aluminum film 320 is made of silicon 100.
Is formed directly on the surface of. However, when the aluminum film 320 is directly formed on the surface of the silicon 100 as described above, there is a problem that the interface is likely to become an aluminum-silicon alloy, the interface characteristics become unstable, and the ventration occurs.

Generally, in such a case, it is preferable to form a thin film of TiN, TiW or tungsten as a barrier metal on the surface of silicon 100 and then form an aluminum film thereon, as shown in FIGS. 4c and 4d. And therefore here
It is necessary to selectively grow aluminum on the barrier metal such as tungsten. In the following, description will be made exclusively on the structure.

Further, when pure aluminum is used, if the density of the current passing through the aluminum wiring is large, there is a problem that aluminum atoms move due to electromigration, causing disconnection or short circuit of the wiring. For this purpose, it is known to use an aluminum-silicon alloy in which a small amount of silicon is introduced into aluminum, and it is necessary to fill the recess with an aluminum-silicon alloy instead of pure aluminum. The aluminum-silicon alloy referred to here includes those in which silicon is segregated in aluminum.

As a method of filling the recess with this aluminum-silicon alloy, there is already a bias sputtering method as one method of flattening technology, and an aluminum-silicon material is used as a target material. It is possible to form a thin film of an aluminum-silicon alloy on the substrate 2 ″ to fill the recess as shown in FIG. 1). However, this method also has a drawback, and when the method is used, the device is There are problems such as large plasma damage.

By the way, Fig. 5 shows a patent application filed by the applicant of the present application.
FIG. 6 is a schematic front cross-sectional view of the same device as the thin film forming device shown in No. 62-172374 “Film forming device and method”.

Reference numeral 1 denotes a processing chamber, which has a structure that can be kept airtight. Reference numeral 3 denotes a substrate holder that is installed in the processing chamber 1 to hold the substrate 2 and adjust the temperature of the substrate 2. The structure of the temperature adjusting means 20 for adjusting the temperature of the substrate holder 3 will be described. 4 is a heater for heating the substrate holder 3 by resistance heating, and 5 is a thermocouple for monitoring the temperature of the substrate holder 3. There is. A temperature measuring resistor may be used instead of the thermocouple 5 as a temperature monitor.

The signal obtained by measuring the temperature with the thermocouple 5 is input to a control circuit such as PID control, PI control, ON-OFF control (not shown), and the input power of the heater 4 is adjusted using a thyristor or a relay. The temperature of the substrate holder 3 is adjusted. When necessary, the substrate holder 3 can be cooled with a water cooling device or the like to adjust the temperature by both heating and cooling methods.

The distribution plate 31 as a gas distribution means distributes the gas uniformly to the substrate 2.
The temperature adjusting means 40 for adjusting the temperature of the distribution plate 31 is provided for supplying to the surface of the heating means 41, the temperature monitor 4
2 and feedback control means (not shown) are mainly configured, and the heating means 41 is adapted to resistance-heat the distribution plate 31 from the atmospheric pressure side by the heater 32. Although the feedback control means is not shown, this is also a thermocouple 33
The signal obtained by measuring is fed back to the control circuit for PID control, PI control, ON-OFF control, etc., and the input power of the heater 32 is adjusted using a thyristor or relay to control the temperature of the distribution plate 31. There is. The heater 32 is insulated from the distribution plate 31 by using an insulating powder 34. Reference numeral 35 is a lid for fixing the insulating powder 34.

When triisobutylaluminum and disilane gas are introduced from a gas supply device (not shown) through the valve 7 to the thin film forming apparatus configured as described above, (Japanese Patent Application No. 63-22463 filed previously by the applicant of the present application) The method described in “Thin film manufacturing method”) can form a good quality aluminum-silicon alloy film on the entire surface of the substrate 2.

(Problems to be Solved by the Invention) However, in the apparatus and method of the above-mentioned patent application,
The aluminum-silicon alloy film is only formed on the entire surface of the substrate, and the aluminum-silicon alloy film cannot be selectively formed at a desired position on the surface of the substrate. For example, as shown in the enlarged cross-sectional view of the surface of the substrate similar to the above in FIG. 4d, when the above-described apparatus and method are applied to the substrate 2 ″, the aluminum-silicon alloy film 33 is formed.
Since 0 is only formed on the entire base 2 ″, there is a problem in that the surface of the base is severely roughened to make it difficult to miniaturize the device.

(Object of the Invention) It is an object of the present invention to solve this problem and to provide an apparatus and a method capable of selectively forming a desired thin film on a desired portion of a substrate surface and performing planarization. .

(Means for Solving the Problem) The present invention provides a processing chamber that can be kept in a vacuum; a substrate holder that is installed in the processing chamber and holds a substrate made of a material that can sufficiently transmit radiation irradiation; Gas introducing means for introducing a predetermined gas into the processing chamber; exhaust means for exhausting the processing chamber; installed in the processing chamber with an opening facing the substrate holder or provided as a part of the processing chamber The gas distribution means for uniformly supplying the predetermined gas introduced from the gas introduction means to the surface of the substrate; and the temperature adjustment means for adjusting the temperature of the gas distribution means;
A thin film forming apparatus provided with a radiation irradiating means for irradiating radiation for heating a desired portion on the surface of the substrate from the back side of the substrate is used. Further, the predetermined gas contains at least two kinds of gases, one of the two kinds of gas is a gas of a compound containing aluminum or a mixed gas thereof (hereinafter, aluminum containing gas), and the other is other than aluminum. Which is a gas of a compound containing a metal or a mixed gas thereof (hereinafter referred to as a metal-containing gas), and out of two or more kinds of different thin films preliminarily formed on the substrate, only a specific thin film is obtained by using a radiation irradiation means. A thin film manufacturing method is used in which the substrate is partially heated by heating to selectively form an alloy film of aluminum and a metal other than aluminum only on the specific thin film.

(Operation) FIG. 2 shows (Japanese Patent Application No. 62-17 filed by the applicant of the present application.
2374 “Film forming apparatus and method”, refer to the method shown in Japanese Patent Application No. 63-22463 “Thin film manufacturing method”, and use a mixed gas of triisobutylaluminum and disilane gas as described later. The relationship of the film formation rate with respect to the substrate temperature when an aluminum-silicon alloy is produced is shown.

As can be seen in the figure, only a desired portion on the substrate is partially heated, the temperature of that portion is kept at 250 ° C or higher, and the other portion is kept lower than 250 ° C, so that the high temperature portion can be selectively heated. Silicon alloys can be deposited.

(Example) FIG. 1 is a front sectional view of a thin film forming apparatus of an example of the present invention. The same members as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

The distribution plate 31 as a gas distribution means is provided in order to uniformly supply the gas to the surface of the substrate 2. In the case of the present embodiment, a large number of small holes through which the gas passes are provided. It has a structure in which four thin plates are stacked with a narrow gap between each other. This number is selected to evenly distribute the gas, and the number of sheets is not limited to this structure. Copper is used for the thin plate because it has good thermal conductivity. The temperature of the distribution plate 31 is adjusted by the temperature adjusting means 40.

When a gas is introduced into the processing chamber 1 through a valve 7 from a gas supply device (not shown), the gas is heated by passing through a distribution plate 31 composed of four thin plates, and the heated gas is uniformly supplied onto the substrate 2. . The heating of this gas has a very large effect on the properties of the film obtained on the substrate.
(Patent application 62
-172374 "Film forming apparatus and method". Then, for example, when the temperature of the entire substrate 2 is set to a certain temperature, film formation is performed on the substrate 2 at the film formation rate as shown in FIG. However, the present invention uses a method of forming a partial temperature difference on the surface of the substrate 2 in order to selectively form a desired thin film only on a desired portion.

Partial heating of a desired portion on the surface of the substrate 2 is performed by the infrared lamp 50. The absorption efficiency of the infrared rays 55 emitted from the infrared lamp 50 is high in the case of a metal such as tungsten, but low in the case of silicon or silicon dioxide, and the absorption efficiency varies depending on the substance. Therefore, by utilizing the difference in absorption efficiency, only a desired portion can be partially heated.

Since the purpose is partial heating, the radiation to be used may be electromagnetic waves other than infrared rays as long as the absorption efficiency is different, and microwaves or ultraviolet rays can also be used.

It is widely recognized by those skilled in the art that the prior art utilizing the partial heating already includes the selective tungsten growth method as described above, and the partial heating is possible and effective.

The materials of the substrate 2 and the substrate holder 3'holding the substrate 2 and the optical window 51 are infrared rays 55 emitted from the infrared lamp 50.
Is sufficiently transparent.

Although quartz glass is used for the optical window 51 in this embodiment, the material is not limited to quartz glass as long as it can sufficiently transmit the infrared rays 55. Further, although a halogen lamp is used as the infrared lamp 50, the infrared lamp 50 is not limited to this, and a laser or the like may be used instead of the lamp.

An aluminum-silicon alloy film can be selectively formed on a desired portion of the surface of the substrate by using the apparatus shown in FIG.

FIG. 3 is an enlarged cross-sectional view of a substrate showing a step of selectively depositing an aluminum-silicon alloy film according to the present invention.

First, as shown in FIG. 3a, 1 is placed on the silicon substrate (Si substrate) 100.
A silicon dioxide film (SiO2) 200 of about 0000Å is formed by a method such as thermal CVD, sputtering method, plasma CVD method, plasma ECR method or the like. Then, the resist is patterned to form the contact hole 21 by the RIE method (FIG. 3b).

Then, by using the selective tungsten growth method, the base 2 ″ of FIG. 3c, which is formed by forming tungsten 400 serving as a via metal at about 1000 Å at the bottom of the contact hole 21, is used as the book of FIG. The apparatus is installed in the apparatus of the invention, the temperature of the distribution plate 31 is set to 230 ° C., a mixed gas of disilane gas at a flow rate of 10 sccm and triisobutylaluminum (using argon as a carrier gas) at a flow rate of 40 sccm is introduced through a valve 7. The pressure is set to 2 Torr by opening and closing the valve 9. In this state, the infrared lamp 5
When the substrate 2 was irradiated with infrared rays 55 radiated from 0, the tungsten 400 was partially heated, and the aluminum-silicon alloy film 340 could be selectively formed thereon as shown in FIG. 3d.

Although isobutylaluminum is used as the aluminum-containing compound in the above, similar results were obtained when other aluminum-containing compounds such as trimethylaluminum and triethylaluminum were used. But with trimethylaluminum and triethylaluminum,
There was a drawback that some carbon remained in the produced film.

Similar deposition can be obtained by using monosilane or trisilane as the silicon compound in addition to disilane. Trisilane has been found to be more effective than disilane, but it is currently difficult to obtain a large amount of high-purity trisilane, and there is a problem in economic efficiency.

Further, in the above, the production of the aluminum-silicon alloy film is described, but the same work can be performed also in the production of the aluminum simple substance film, the aluminum-copper alloy film, the aluminum-silicon-copper alloy film and the like.

(Effects of the Invention) As described above, with the apparatus and method of the present invention, it is possible to selectively form a thin film on the bottom or the recess of a substrate having a step or a recess and planarize the substrate.

[Brief description of drawings]

FIG. 1 is a sectional view of a thin film forming apparatus according to an embodiment of the present invention. FIG. 2 is a relationship diagram between the substrate temperature and the film formation rate. FIG. 3 is an enlarged cross-sectional view of the surface of the substrate showing the process of producing the aluminum-silicon alloy film according to the present invention. FIG. 4 is an enlarged cross-sectional view of the substrate surface showing the state of the thin film produced by the conventional thin film production method. FIG. 5 is a sectional view of a conventional thin film forming apparatus. 1 ... Processing chamber, 2 ... Substrate, 3 '... Substrate holder, 31
...... Gas distribution means, 32 …… Heater, 33 …… Thermocouple, 40
...... Temperature adjustment means, 50 ...... Infrared lamp, 51 ...... Optical window, 55 ...... Infrared.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-55-67135 (JP, A) JP-A-63-14870 (JP, A) JP-A-56-45759 (JP, A) JP-B-44- 5283 (JP, B2)

Claims (3)

(57) [Claims] 1. A processing chamber capable of maintaining a vacuum; a substrate holder installed in the processing chamber for holding a substrate; gas introducing means for introducing a predetermined gas into the processing chamber; and exhausting the processing chamber. An exhausting means for controlling the opening of the substrate to be installed in the processing chamber or provided as a part of the processing chamber so that a predetermined gas introduced from the gas introducing means is uniformly applied to the surface of the substrate. A gas distribution means for supplying a gas to the substrate; and a substrate heating means; and a part of elements constituting the predetermined gas are deposited on the surface of the substrate to form a thin film. Has a gas distribution plate temperature adjusting means for heating the predetermined gas passing through the gas distribution means, independently of the temperature in the processing chamber. Place on the surface Radiation irradiating means for irradiating radiation to heat a desired portion is provided, and the substrate holder is made of a material that can sufficiently transmit the radiation irradiation. A thin film forming apparatus characterized by depositing an alloy film with a metal. 2. A method for producing a thin film by depositing a part of constituent elements of a gas introduced into a processing chamber on a surface of a substrate by heating only the substrate, the gas comprising at least two kinds of gases. One of the two kinds of gas is a gas of a compound containing aluminum or a mixed gas thereof (hereinafter referred to as an aluminum-containing gas), and the other is a gas of a compound containing a metal other than aluminum or a mixed gas thereof ( (Hereinafter referred to as metal-containing gas), the two types of gas are heated on the gas introduction path and then introduced into the processing chamber, and a desired portion of the substrate is partially heated using a radiation irradiating means. Method for producing a thin film, characterized in that an alloy film of aluminum and a metal other than aluminum is produced on the surface of the desired portion. 3. The method for producing a thin film according to claim 2, wherein the metal other than aluminum is silicon and the thin film produced is an aluminum-silicon alloy film.