JPH04333223A - Film forming method and device thereof - Google Patents

Abstract

PURPOSE:To form a metal film on a semiconductor substrate in an excellent selective manner. CONSTITUTION:HCl gas is introduced into a pretreatment chamber 101 from a gas introducing hole 107. A semiconductor substrate 302, provided on a susceptor 103, is heated up by a heater 104 while ultraviolet rays are being emitted from an ultraviolet ray lamp 106. After the pretreatment has been finished, a gate valve 108 is opened, the semiconductor substrate 302 is moved into a reaction chamber 301, and a metal film is selectively formed on the semiconductor substrate 302 using a selective CVD method. As the metal growth point such as contaminants, damages and the like on an insulating film generated in the pretreatment can be inactivated, the metal film can be formed on the semiconductor substrate in an excellent selective manner.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming method and a film forming apparatus for selectively forming a metal film on a semiconductor substrate by selective CVD.

0002

2. Description of the Related Art FIG. 3 is a sectional view showing a conventional selective CVD apparatus used in selective CVD. In the figure, 30
1 is a reaction chamber, 302 is a semiconductor substrate on which an insulating film with contact holes is formed, and 303 is a semiconductor substrate 3.
02 is a susceptor installed, 304 is a heater for heating the susceptor 303, 305 is a heating power source that supplies electricity to the heater 304, and 306 is a gas inlet.

FIG. 4 is a cross-sectional view of a semiconductor substrate in which a metal film is formed in a contact hole by the selective CVD apparatus described above. An insulating film 402 having a contact hole 405 is formed on the semiconductor base layer 401 . A metal film 403 formed by selective CVD is embedded in the contact hole 405 . 404 is a metal film formed on the insulating film 402.

Next, the case where the metal film 403 is buried in the contact hole 405 by selective CVD method will be explained. First, a semiconductor substrate 302 is placed on a susceptor 303. The reaction chamber 301 is then evacuated by evacuation. Furthermore, the semiconductor substrate 302 is heated by supplying electricity from the heating power source 305 to the heater 304 to heat the susceptor 303 .

Next, raw material gases (tungsten hexafluoride (WF6), silane (SiH4)) are introduced into the reaction chamber 301 from the gas inlet 306 and supplied to the surface of the semiconductor substrate 301. At this time, the source gas flows through the contact hole 40.
Semiconductor base layer (Si) 401 exposed through 5
reacts. Therefore, as shown in FIG. 4, the semiconductor base layer 401 exposed through the contact hole 405
A metal film (tungsten) 403 is formed thereon. Unreacted gas and by-products are exhausted to the outside by an exhaust system. By optimizing the flow rate of the source gas, the gas pressure of the source gas, and the processing temperature, a metal film (tungsten) can be formed only on the surface of the semiconductor base layer 401 exposed through the contact hole 405. The reason why the metal film is formed only on the semiconductor base layer 401 in this way is that
This is because there is a large difference in the probability of absorption of source gas on the solid surface and catalytic action between semiconductors and insulators.

[0006]

[Problems to be Solved by the Invention] Since the conventional selective CVD method is carried out through the steps described above, contaminants generated in the process of forming the contact hole 405, etc. and the insulating film 4
Damage on 02 (if the insulating film is SiO2, SiO2
There may be metal growth points on the insulating film 402 due to X (portion where X is smaller than 2). Due to the presence of this metal growth point, a metal film 404 may be formed outside the contact hole 405, that is, on the insulating film 402, as shown in FIG. Then, when metal wiring is formed on this, there is a problem that a short circuit occurs between the metal wirings due to the metal film 404 on the insulating film 402, and a normal semiconductor device cannot be obtained.

The present invention was made to solve the above-mentioned problems, and its purpose is to provide a film forming method and a film forming apparatus that can form a metal film on a semiconductor substrate with good selectivity. do.

[0008]

[Means for Solving the Problems] A film forming method according to the present invention includes a step of heat-treating a semiconductor substrate while irradiating ultraviolet rays in an atmosphere containing chlorine gas, and after the heat treatment, the semiconductor substrate is subjected to a selective CVD method. selectively forming a metal film thereon.

The film forming apparatus according to the present invention includes a pretreatment chamber in which a semiconductor substrate is subjected to heat treatment while irradiating ultraviolet rays in an atmosphere containing chlorine gas; A selective CVD reaction chamber is provided for selectively forming a metal film by a selective CVD method on the semiconductor substrate processed by the apparatus.

0010

[Operation] In this invention, before a metal film is selectively formed on a semiconductor substrate by the selective CVD method, the semiconductor substrate is heat-treated while being irradiated with ultraviolet rays in a gas atmosphere containing chlorine. Metal growth points such as contaminants on the insulating film are inactivated.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of a film forming apparatus for implementing the film forming method according to the present invention. 10
1 is a pretreatment chamber provided adjacent to the selected CVD reaction chamber 301; 103 is a susceptor; 104 is a heater for heating the susceptor 103; 105 is a heating power source that supplies electricity to the heater 104; An ultraviolet lamp for irradiating the installed semiconductor substrate 302 with ultraviolet rays; 107 a gas inlet for introducing a gas containing chlorine into the pretreatment chamber 101; 108 a reaction chamber 301 and the pretreatment chamber 10;
This is a gate valve that can be opened and closed freely provided at the boundary of 1. The rest of the configuration is the same as the conventional device shown in FIG.

Next, the operation will be explained. First, in order to perform pretreatment, the semiconductor substrate 302 is placed on the susceptor 103 in the pretreatment chamber 101. The pretreatment chamber 101 is then evacuated to a vacuum. Furthermore, the semiconductor substrate 302 is heated to, for example, about 400° C. by supplying electricity from the heating power source 105 to the heater 104 to heat the susceptor 103.

Next, the semiconductor substrate 302 is irradiated with ultraviolet light by the ultraviolet lamp 106 . Further, the semiconductor substrate 302 is heated by the heater 104 while introducing a chlorine-based gas (for example, HCl gas) into the pretreatment chamber 101 from the gas inlet 107 . At this time, the flow rate of HCl gas is, for example, about 20
0 sccm, the pressure is, for example, about 5 Torr, and the processing time is, for example, 5 minutes. Through this treatment, trace amounts of metal contaminants present on the insulating film 402 are converted into metal chlorides, vaporized, and removed. Further, damage on the insulating film 402 is inactivated. Specifically, unbonded portions of Si constituting the insulating film 402 are bonded with chlorine (Cl) and inactivated. In this way, active portions (metal contaminants, damage) on the insulating film 402 that serve as metal growth points can be inactivated. Note that the gate valve 108 is closed while the above processing is being performed.

Next, supply of chlorine gas, semiconductor substrate 302
UV irradiation and heating of the semiconductor substrate 302 are stopped, and the pretreatment chamber 101 is evacuated by the exhaust system. After that, the gate valve 108 is opened and the semiconductor substrate 302 that has been pretreated as described above in the pretreatment chamber 101 is transferred to the pretreatment chamber 101.
from there to the reaction chamber 301. Then, as in the conventional method, a metal film is selectively formed on the semiconductor substrate 302 by the selective CVD method. Since the metal growth points on the insulating film 402 are inactivated by the treatment in the pretreatment chamber 101, no metal film is formed on the part other than the contact hole 405, that is, on the insulating film 402. Therefore, when metal wiring is formed on this, there will be no short circuit between the metal wiring.

[0015] As a result of performing the pretreatment under the conditions set forth above, it was confirmed that a very good effect could be obtained. In addition, when UV irradiation is not performed (pretreatment chamber 101
It was also confirmed that the above-mentioned effects were impaired when only heat treatment was performed in an HCl gas atmosphere.

Furthermore, UV irradiation activates the reaction between unbonded Si and chlorine (Cl), and the above effect can be obtained even at a low temperature of about 400°C. The present invention can also be applied to the case of processing a semiconductor substrate having melting point metal wiring.

[0017]Furthermore, although it has been conventional practice to surface-treat a semiconductor substrate using plasma and then form a metal film by selective CVD, the present invention provides an apparatus for surface-treating a semiconductor substrate using plasma. This eliminates the need to use plasma, which simplifies the configuration, and also eliminates unnecessary damage to the semiconductor substrate caused by plasma.

[0018]

[Effect of the invention] As described above, according to this invention, selection C
Before selectively forming a metal film on a semiconductor substrate using the VD method, the semiconductor substrate is heat-treated while being irradiated with ultraviolet rays in a gas atmosphere containing chlorine. Metal growth points are inactivated by actions such as turning into metal chlorides and vaporizing them. As a result, there is an effect that a metal film can be formed with high selectivity on a semiconductor substrate by the selective CVD method.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a film forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view of a semiconductor substrate manufactured by the apparatus shown in FIG. 1.

FIG. 3 is a sectional view showing a conventional selective CVD apparatus.

FIG. 4 is a cross-sectional view of a semiconductor substrate manufactured by the apparatus shown in FIG. 3.

[Explanation of symbols]

101 Pretreatment chamber 103,303 Susceptor 104,304 Heater 105,305 Heating power supply 106 Ultraviolet lamp 107,306 Gas inlet 108 Gate valve 301 Reaction chamber 302 Semiconductor substrate

Claims (2)

[Claims] 1. A step of heat-treating a semiconductor substrate while irradiating ultraviolet rays in an atmosphere containing chlorine gas, and a step of selectively forming a metal film on the semiconductor substrate by a selective CVD method after the heat treatment. A method for forming a film. 2. A pretreatment chamber for heat-treating a semiconductor substrate while irradiating ultraviolet rays in an atmosphere containing chlorine gas; A film forming apparatus comprising a selective CVD reaction chamber for selectively forming a metal film.