JPH04293776A - Thermal cvd method - Google Patents

Abstract

PURPOSE:To provide a patterned transfer thermal CVD method with good space selectivity by using spacially shaped light. CONSTITUTION:The light 14 of microwavelength, such as synchrotron radiation light, is spacially shaped by a mask 15 and the surface of a poly-Si film 13 is irradiated with this light in the presence of gaseous raw materials, by which the surface compsn. of the irradiated part is changed to the compsn. which substantially obviates the generation of thermal CVD prior to a thermal CVD stage. A CVD film grows only in the part irradiated with the light in the next thermal CVD in this way. Since the wavelength of the light with which the film is irradiated is short, the film patterned as if the aperture shape of the mask 15 is reversed is formed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to CVD (c) of various materials.
chemical vapor deposition)
In particular, the present invention relates to a thermal CVD method that uses light to perform patterning with excellent spatial selectivity without processes such as resist coating, exposure, and resist peeling.

0002

[Prior Art] As a conventional example of a method of directly patterning a CVD film by irradiating light during thermal CVD and suppressing the growth of the CVD film in the light irradiated area, there is a patent application filed in Japanese Patent Application No. 60-254582 invented by Kishida. Example of "Surface selective treatment method" and Sugita et al.'s presentation at the 36th Applied Physics Association Lecture (Spring 1989) Lecture No. 2p-L-5 "Positive pattern transfer CVD using synchrotron radiation" There is. To summarize these methods, the adsorbent can be detached by infrared light irradiation that resonates with the vibrational energy of the bond between the substrate and the adsorbent, or the adsorbent can be detached by cutting the bond between the substrate and the adsorbent by vacuum ultraviolet light irradiation. It uses detachment.

0003

[Problem to be solved by the invention] C by the above conventional method
A method for patterning a VD film is to perform patterning by irradiating light only onto a desired portion of a substrate and suppressing CVD at the light irradiated portion. Suppression of CVD,
When the adsorbent is detached by irradiation with infrared light that resonates with the vibrational energy of the bond between the substrate and the adsorbent, the substrate is heated by the infrared light, so the adsorbent is not only detached but also deposited by thermal decomposition. occurs, and CVD control becomes insufficient. In addition, when suppressing CVD by detaching the adsorbent by breaking the bond between the substrate and the adsorbent by irradiating the substrate with vacuum ultraviolet light,
Photochemical CVD occurs due to not only bond cleavage between adsorbents but also bond cleavage within the adsorbent, and CVD suppression becomes insufficient.

[0004] In addition to the insufficiency caused by such a CVD suppression mechanism, there are also restrictions on the type of light source. In the method of detaching adsorbents by irradiation with infrared light that resonates with the vibrational energy of the bond, it is necessary to make the energy of the irradiated light resonate with the vibrational energy. In addition, since there is usually more than one type of adsorbent, in order to desorb all the adsorbents, it is necessary to use light that resonates with each of the adsorbents, which increases the number of light sources that must be prepared and makes it difficult to configure the device. becomes a hindrance. On the other hand, in the method of detaching the adsorbent by breaking the bond between the substrate and the adsorbent using ultraviolet light irradiation, this is done by moving the electrons in the bonding orbital to the antibonding orbital through valence electron excitation of the adsorbent. . This means that the initial state and final state of photoexcitation are determined, so
It is limited to the use of light with a wavelength corresponding to this energy. In addition, when using vacuum ultraviolet light with an even shorter wavelength, ionization of the adsorbent occurs, which breaks the bond between the adsorbent and the substrate, causing detachment of the adsorbent and inhibiting CVD in the vacuum ultraviolet light irradiation region. It can be suppressed. In this case, the energy of the light used only needs to be greater than the ionization threshold energy, so the restrictions on the wavelength are less strict than in the above two methods. However, ionization by valence electron excitation has a problem in that CVD caused by adsorbent desorption is still insufficiently suppressed.

[0005] Furthermore, there is a problem in patterning the CVD film due to the diffraction effect of light. The light irradiation area is determined by the shape of the opening in the mask, and the sharpness of the edge shape of the CVD film after patterning is the best way to suppress light from going around to non-irradiated areas due to light diffraction at the opening in the mask. Depends on. Since the magnitude of this wraparound is proportional to the wavelength of the light, it is better to use vacuum ultraviolet light, which has a shorter wavelength, than to use infrared light to suppress the wraparound of light due to diffraction. However, the wavelengths used so far are still insufficient to suppress diffraction effects.

An object of the present invention is to achieve effective CV in the light irradiation section.
In addition to suppressing D, a wide selection range of light sources that emit the desired wavelength can be obtained, and at the same time, the diffraction effect of light is suppressed.
It is an object of the present invention to provide an inversion patterning thermal CVD method that has a sharp edge at the boundary between a light irradiated part and a non-irradiated part and has good spatial selectivity.

[0007]

[Means for solving the problems] Patterning C of the present invention
According to the VD method, in the thermal CVD method, prior to the thermal CVD step, the substrate is irradiated with light in the presence of a CVD source gas to make the surface of the irradiated part have a composition different from that of the non-irradiated part. By suppressing the CVD reaction at the irradiated part in the subsequent thermal CVD step,
Thermal CVD characterized by patterning a VD film
provide a method. In addition, a Si substrate is used as the substrate, and C
A thermal CVD method characterized in that dimethylaluminum hydride is used as a VD source gas to grow Al. In addition, the temperature range in which thermal CVD is performed is 150
Provided is a thermal CVD method characterized in that the temperature is between .degree. C. and 300.degree.

[0008]

[Operation] The operational feature of the present invention is that the substrate surface composition in the light irradiated area is changed from that in the non-irradiated area to suppress the reaction of the CVD raw material gas in the light irradiated area.

The action of the present invention is based on Si made from dimethylaluminum hydride (DMAH).
FIG. 2 shows the experimental results of the temperature dependence of the growth rate obtained in the above CVD of Al. 150℃～30
In the temperature range of 0°C, A by irradiation with light around 4 nm
Since the growth rate is suppressed to zero, Al can be grown only in the non-irradiated areas. Further, as a result of Auger composition analysis, it was found that the irradiated part was covered with AlC, and the thickness of the film was 2 nm or less, based on the Auger electron escape depth of the Si substrate. This growth suppressing effect in the irradiated area continues for 90 minutes or more after the light irradiation is stopped, as shown in FIG. 3, where the intensity of the Auger electron signal of Si on the substrate remains constant for 90 minutes or more.

[0010] Therefore, using the results obtained above,
DMAH adsorbed on the substrate prior to Al CVD
By photolyzing and patterning an AlC thin film to grow only on the light irradiated area, and then performing CVD of Al at a desired temperature of 300°C or less of the substrate, Al is grown only on the areas where there is no AlC thin film. You can grow.

[0011] Furthermore, in order to perform highly accurate patterning such that the patterned shape of the AlC thin film is transferred from the shape of the opening of the mask, it is sufficient to suppress the diffracted light diffracted at the edge of the opening of the mask. When the wavelength of the light used is short enough to excite the inner shell, the intensity and wrap-around of the diffracted light are two to three orders of magnitude smaller than the infrared rays and vacuum ultraviolet light that have been used so far that can excite valence electrons. As a result, CVD can be suppressed only by the irradiation section with straight-going light, and CVD can be formed into the desired shape.
D film can be patterned.

0012

[Embodiment] The present invention will be explained below with reference to FIG. In this example, in the formation of a Si device,
The case of forming Al wiring will be described.

FIG. 1(a) shows that a thermal oxide film 12 on a Si substrate 11 is patterned, and p is applied to the entire surface of the thermal oxide film 12.
A structure in which an oly-Si film 13 is formed is shown.

FIG. 1(b) shows a method of directly patterning the non-wiring area of the substrate of FIG. 1(a) using light 14. In FIG. The substrate having the structure shown in FIG. 1(a) is mounted in a CVD chamber, and raw material gas Al(CH3)2H is supplied into the chamber through a mask 15 having an opening in a portion corresponding to a non-wiring formation area. , irradiates the light 14. As a result, Al(CH3)2 adsorbed on the surface
The H molecules are photodecomposed and an AlC thin film 16 is formed. The light 14 used here was synchrotron radiation with an energy higher than 100 eV that can excite the inner shells of Al atoms, Si atoms, and C atoms. Next, the irradiation of the light 14 is stopped, and Al(C
H3) While supplying 2H, increase the substrate temperature to 200℃.
When the temperature is raised to .degree. C., Al grows only in areas where the AlC thin film 16 is not present, as shown in FIG. 1(c), and an Al wiring 17 can be formed. After this, using the deposited Al as a mask, pol
The Al wiring formation process is completed by removing the y-Si by plasma etching. After forming the Al wiring using this method, there was no electrical leakage between this wiring and the wiring with no contact formed therein.

[0015] In this example, the inversion CVD of Al using Al(CH3)2H as a raw material was described, but the raw material is not limited to this, and Al-iso(C4H9
) 3, etc., or may contain a chlorine atom. Further, the substrate is not limited to the embodiment, and other semiconductor substrates are also effective. In addition, materials that undergo reverse CVD are not limited to Al, but include metals such as Cu and Au, as well as Si and G.
It may be a semiconductor such as aAs or a mixed crystal thereof, or S
An insulating film such as iO2 may also be used. Depending on what is to be grown, growth conditions such as the substrate, raw material gas, light energy, and substrate temperature may be changed to suit the principle described in the section of operation.

[0016]

According to the present invention, in CVD of various materials, it is possible to provide a thermal CVD method that allows patterning with good spatial selectivity by using light without processes such as resist coating, exposure, and resist peeling.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a wiring forming method according to the present invention.

FIG. 2 is a diagram showing the experimental results of the temperature dependence of the Al growth rate in the synchrotron radiation irradiated area and the non-irradiated area, which is the basis of the action of the present invention.

FIG. 3 is a diagram showing experimental results showing that the effect of suppressing Al growth in the synchrotron radiation irradiation area, which is the basis of the action of the present invention, persists even after irradiation is stopped.

[Explanation of symbols]

11 Si substrate 12 Thermal oxide film 13 Poly-Si film 14 Light 15 Mask 16 AlC thin film 17 Al wiring

Claims (3)

[Claims] 1. In a thermal CVD method, prior to the thermal CVD step, the substrate is irradiated with light in the presence of a CVD source gas to make the surface of the irradiated part have a composition different from the surface composition of the non-irradiated part. By suppressing the CVD reaction at the irradiated part in the subsequent thermal CVD step,
Thermal CVD characterized by patterning a VD film
Method. 2. The thermal CVD method according to claim 1, wherein dimethylaluminum hydride Al(CH3)2H is used as the CVD source gas. [Claim 3] The temperature range for performing thermal CVD is from 150°C to
The thermal CVD method according to claim 2, characterized in that the temperature is between 300°C.