JPS61136682A - Laser cvd - Google Patents

Abstract

PURPOSE:To deposit a thin film having a desired width on a substrate by a laser CVD method by using a gaseous mixture composed of H2 and N2 for the carrier gas of an alkyl compd. and changing the mixing ratio of the gaseous mixture to change the decomposition temp. of the alkyl compd. CONSTITUTION:Laser light 12 is irradiated through a window 22 to the deposition part 13 on a substrate 11 on the surface of which the patterns of Si 20 and SiO2 21 intermingle to heat the substrate. The Al(CH3)3 transported by the gaseous mixture composed of gaseous H2 14 and gaseous N2 15 is decomposed and Al is deposited on the substrate 11. The substrate 11 and a cell 16 for deposition are slid on a stage 18 by a motor 19 so that the Al is deposited straightly. The mixing ratio is set at about H2:N2=1:1 and the total flow rate at about 700cc/min in the case of deposition on the Si 20 and the mixing ratio is set at H2:N2=1:9 in the case of deposition on the SiO2 21. The straight and uniform deposition of the Al at about 3mu width is thus made possible with substantially no change in the line width of the Al at the boundary line between the Si 20 and the SiO2 21 by changing the mixing ratio on the Si 20 and the SiO2 21 in the above-mentioned manner.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for depositing a thin film with a desired width on a substrate patterned with different materials in an optical CVD method and a direct writing laser CVD method. It is related to.

(Prior art and its problems) In conventional laser CVD, a mixed gas of source gas and carrier gas is introduced into a deposition cell, the substrate is selectively irradiated with laser light, and the source gas is decomposed by the heat. The desired film, such as metal or semiconductor, was deposited using the method. The direct drawing of the line can be performed while moving the deposition cell mounted with the substrate relative to the laser beam using a moving mechanism.

For example, in Applied Physics Letters (Appl.
In the paper published on pages 957 to 959 of Volume 39 (Phys, Lett, ), SiH4 to S
In order to deposit 5i02, the wafer is heated by scanning the wafer with an Ar+ laser beam including the portion where 5i02 has been removed, thermally decomposing SiH4, and depositing Si. However, the line width of linearly deposited Si was wider on 5i02, which has a smaller thermal conductivity, than on Si, which has a higher thermal conductivity, and Si could not be deposited with a uniform width on different underlying materials. Therefore,
In anticipation of the broadening of the Si line width, the wiring spacing had to be thickened, which was a major problem in achieving high integration.Also, when depositing A/ from At(CH3)3, I had a similar problem.

(Object of the Invention) The object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide a method for forming a substrate on which various underlying materials are patterned and intricate.
An object of the present invention is to provide a method for linearly depositing metals, semiconductors, etc. with a desired width by direct laser CVD.

(Structure of the Invention) The present invention provides a laser CVD method for selectively forming a thin film on a substrate using a CVD source gas containing an alkyl compound, in which N2 and an inert (or N2) gas are used as a carrier gas for the alkyl compound. The present invention is characterized in that the decomposition temperature is controlled by using a hybrid gas and changing the mixing ratio of the mixed gas.

(Operation/Principle of the Invention) The present invention solves the problems of the prior art by using the method described above. In the extensive CVDX experiments conducted by the inventor of the present invention, thermal decomposition of a compound bonded to a methyl group in an inert gas or N2 gas among alkyl compounds that are raw material gases is a radical reaction; It was found that hydrogenation reactions occur at lower temperatures.

In addition, thermal decomposition of compounds bonded to ethyl, propyl, and butyl groups in inert (or N2) gas or N2 gas occurs by the so-called p-elimination mechanism; The reaction was found to occur at lower temperatures.

Utilizing this new knowledge that the decomposition reaction temperature of alkyl compounds differs depending on the type of carrier gas, it is possible to intentionally adjust the decomposition reaction temperature between the upper and lower limits by mixing multiple types of carrier gas and changing the mixing ratio. A new industrial method of control becomes possible. Figure 1 (
a) In (b), Ae (C2H5)a, Ga is added to the raw material gas.
An example using (CH3)a and Ga(C2Hs)a will be shown.

Therefore, when depositing various thin films by direct laser thermal CVD on substrates containing a variety of underlying materials, the N2 gas content may be reduced to reduce the N2 gas content on substrates made of materials or structures with low thermal conductivity. Bring the decomposition reaction temperature of the compound closer to the upper limit. On the other hand, on a substrate made of a material or structure with high thermal conductivity, the content is increased to bring the decomposition reaction temperature closer to the lower limit. In this way, metals, semiconductors, etc. can be deposited with a uniform width on a wafer in which Si, 5iQ2, etc. are mixed, regardless of the underlying material or structure. Further, even on the same substrate, the width of deposition can be intentionally changed by changing the content rate.

(Example) Hereinafter, the present invention will be described with reference to drawings showing examples.

FIG. 2 shows an embodiment to which the present invention is applied.

Substrate 1 with intricate patterns of Si and 5i02 on the surface
The deposited portion 13 on 1 was heated by irradiating it with a laser beam 12 through a window 22, and AmCHs)s transported in a mixed gas of N2 gas 14 and N2 gas 15 was decomposed and Ar was deposited. In order to uniformly mix N2 gas 14 and N2 gas 15, a baffle 17 was attached to the deposition cell 16. Stage drive motor 1 for moving the substrate 11 and deposition cell 16
9, A is deposited by direct drawing by sliding on the moving stage 18. The moving stage 18
I slid it. The laser light power was about 0.5W. A vapor pressure of about 10 Torr of AeCCHa)a was flowed together with the carrier gas. This carrier gas is N2
A mixed gas of gas 14 and N2 gas 15 was used: N2:N2 x 1:1 when depositing on Si20, the total flow rate was about 700 cc/min, and when depositing on 5i0221, it was N2:N2-1:9. . In this way, Si
By changing the mixing ratio between 8.20 and 5i0221, it was possible to uniformly deposit Ae with a width of about 3 pm at the boundary line between 8.20 and 5i0221 by direct drawing without changing the line width. The carrier gas mixing ratio is mass 70
- N2 gas 14 using controller 23 and pulp 24
This was controlled by changing the flow rate of N2 gas 15.

There is a lag time after changing the gas mixture ratio until the gas becomes constant in the deposition cell 16, but this can be solved by the small volume of the deposition cell 16 and by increasing the flow rate when changing the gas mixture ratio. did it.

Ae could also be deposited with a uniform width by using Ae(C2H5)a instead of AC(CHa)a. Furthermore, even when Ar(iso-C4H9)3 was used, Ae could be similarly deposited with a uniform width. Of course, in addition to Ae, there are also Zn, Cd, In, Ga, Te.
, Sb, A, , Hg, P, Si, I
If nP alkyl compounds are used, these metals, semiconductors, and doping substances can also be deposited by applying the present invention.

In addition, N20 and NH are added to alkyl compounds as CVD gases.
It goes without saying that by mixing 3, it is possible to directly deposit an oxide or nitride dielectric by applying the method of the present invention.

Furthermore, although the present invention is effective in eliminating discontinuities in the deposition characteristics at the boundary due to differences in thermal conductivity due to underlying materials and structures, it is not possible to intentionally change the deposition shape. There is no hindrance whatsoever. In other words, it is of course possible to increase the intensity of the irradiated light in order to increase the width or height of the deposition on a predetermined portion of the substrate.'It is also possible to make use of the features of the present invention to lower the decomposition temperature of the CVD gas. Needless to say, the above purpose can be achieved by doing so. Furthermore, although an example in which Si is used as the substrate has been described here, it goes without saying that the application of the present invention is not limited to semiconductor substrates.

(Effects of the Invention) As described above, by applying the laser CVD method of the present invention, various thin films can be deposited with desired widths with high accuracy on a substrate on which various underlying materials are mixed, without being affected by differences in the underlying materials. can be done.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams showing an example in which the decomposition temperature of the raw material gas changes depending on the mixing ratio of the mixed carrier gas, and Figure 2 is a schematic diagram of an apparatus used in an embodiment to which the present invention is applied. . 11...Substrate 12...Laser beam 13...Deposition part 14...
・H2 gas 15...N2 gas 16・
... Deposition cell 17 ... Baffle
18...Moving stage 19...Moving stage driving motor 20''・Si 2
1 ”・810222...Window 23...Mass flow controller 24...
Detection rate of AZ from pulp TEA

Claims (1)

[Claims] In a laser CVD method in which a substrate placed in a CVD source gas containing an alkyl compound is selectively irradiated with laser light to form a thin film on the irradiated area, H_2 and an inert gas are used as a carrier gas for the alkyl compound. A laser CVD method characterized by using a mixed gas of H_2 and N_2 or a mixed gas of H_2 and N_2, and changing the mixing ratio of the mixed gas to change the decomposition temperature of the source gas.