JPS60225431A - Surface treating device - Google Patents

Abstract

PURPOSE:To accomplish thin film formation, etching or impurity doping without damaging a substrate by a method wherein the substrate to be treated is selectively irradiated with the first light in accordance with a pattern on the mask, and the medium gas is dissociated with the second light. CONSTITUTION:The substrate to be treated 2 is vertically irradiated with the first laser beam 7 via mask 10, convergent lens (photo introduction window) 11, and the like. This substrate is irradiated with the second laser beam 13 via photo introduction window 14. In the case of etching, selective resistless etching 24 can be attained without damage by irradiating the surface of a sample simultaneously with the light 13 which dissociates Cl2 molecules. In film formation, the laser beam 13 photo-decomposes by efficient absorption and separates out a metal. Doping enables the selective formation of P type diffused layers on the Si substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to surface treatment using photochemical reactions!&[.

(Technical background of the invention and its problems) In recent years, integrated circuits have been becoming increasingly finer, and prototypes of ultra-LSIs with a minimum pattern size of 1 to 2 [μm] have recently been developed. In microfabrication, such as etching, reactive ion etching is used.
The mainstream technology is eIonEtcoinO;RIE), and in the process of thin film deposition, ion blating methods, plasma CVD methods, etc., which are compatible with low-temperature processes, are widely used. However, all of these technologies are processes that use plasma, and they may cause irradiation damage to the device, such as destruction of the gate oxide film (Furukawa, Watanabe; Proceedings of the 5th Dry Process Symposium, Institute of Electrical Engineers of Japan, Tokyo, 1983). The current situation is that concerns are beginning to be raised.

In contrast to the plasma process described above, research on thin film deposition, etching, impurity diffusion, etc. using photochemical reactions has recently been actively conducted as non-irradiation damage processes that do not use charged particles. This photoexcitation process is difficult to achieve with other current processes.
UP 17 ■ New processes such as blunt doping and oxidation are possible, and since it is essentially a low-temperature process, it is thought to be fully compatible with future submicron device manufacturing processes. However, this type of device has not yet been put into practical use, and its realization is strongly desired.

[Purpose of the invention]

An object of the present invention is to selectively treat a substrate to be treated without causing radiation damage to the substrate! It is an object of the present invention to provide a surface treatment apparatus that can perform treatments such as film formation, etching, and impurity doping, and can perform the above-mentioned treatments without a mask that is formed in close contact with a substrate to be treated.

[Summary of the invention]

The gist of the present invention is to utilize a photochemical reaction and to selectively irradiate light onto a substrate to be processed using a mask spaced apart from the substrate to be processed.

That is, the present invention provides a vacuum container for accommodating a substrate to be processed, a means for introducing gas into the container, a means for exhausting the gas in the container, and a surface to be processed of the substrate. a first light source that vertically irradiates light, a mask disposed between the light source and the substrate to be processed, and on which a desired pattern consisting of light passing portions and non-light passing portions is formed; an optical system that images a pattern onto the substrate to be processed;
a second irradiating light substantially parallel to the surface to be processed of the substrate to be processed;
The surface treatment apparatus is equipped with a light source, and selectively irradiates light from the first light source onto the substrate to be processed according to a pattern on the mask, and selectively irradiates the light irradiation part with light from the first light source. Specifically, thin film formation, etching, or impurity doping is performed.

〔Effect of the invention〕

According to the present invention, by utilizing photochemical reactions, various treatments can be performed on a substrate to be treated without radiation damage. Furthermore, since the mask is placed between the substrate to be processed and the first light source, one distance from the substrate to be processed, it is possible to eliminate the need for seven masks that are in close contact with the substrate to be processed. The effect of not requiring a mask in close contact with the substrate to be processed is extremely effective in semiconductor manufacturing processes. In other words, in conventional processes, when performing selective processing, it was essential to have a mask in close contact with the substrate to be processed, which required a step to remove this mask after the specified processing, complicating the process. . Furthermore, there was a risk that the process of removing the mask would have an adverse effect on the underlying substrate. In addition, since the light from the second light source is passed in parallel over the substrate to be processed, various gases introduced into the vacuum container can be sufficiently dissociated, thereby improving the processing speed. Effects such as this can be obtained.

[Embodiments of the invention]

FIG. 1 is a schematic diagram showing a semiconductor surface treatment apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a vacuum container, and a susceptor 3 on which a substrate 2 to be processed is placed is arranged within the container 1. The susceptor 3 is moved in the horizontal direction (X direction) and the front and back direction (Y direction) in the drawing by a drive mechanism (not shown). Further, the container 1 is provided with a gas inlet 4 for introducing gas and a gas exhaust port 5 for evacuating the inside of the container 1. Here, the container 1
As the gas introduced into the substrate, a reactive gas (etching gas) such as CI2, a deposition gas such as Si(CH3)4, or a doping gas such as PCl3 or BCl3 may be appropriately selected.

On the other hand, above the container 1, a first light source 6 is arranged. For example, w6 is a KrCl excimer laser whose emission center is at a wavelength of 222 [rv], and the light source 6
The laser beam (first light) 7 from
The light is introduced into the container 1 via a tube, etc., and is irradiated vertically onto the substrate 2 to be processed. Here, the mask 10 has a desired pattern 10b made of A1 formed on the lower surface of a fused silica plate 10a. Further, the lens 9.11 is made of fused silica that is transparent to ultraviolet light.

Further, on the left side of the container 1, a second light ll! 12 are arranged. This light source 12 has a wavelength of '3/', for example.
No refit 1-fiN! /Arh, i', jt
ae4V5/N I 〒 Jp' laser beam (second light) 13 from light 1 [112] is introduced into the container 1 through the light introduction window 14, and is applied onto the substrate 2 to be processed. The beam is irradiated parallel to the treatment surface of No. 2. Here, the second light 13 is transmitted to the substrate 2 to be processed.
It is a sheet-like beam wider than the long axis of the. Also, container 1
On the side wall on the other side, there is a light guide window 1 similar to the light guide window 14 described above.
5 is provided. Then, through this window 15, the container 1
The laser beam 13 that has passed through the container is led out to the outside of the container 1,
This prevents the laser beam 13 from being reflected from the inner wall of the container.

Next, the operation of the apparatus configured as described above will be explained.

This apparatus can perform processes such as selective etching, thin film deposition, and doping, and these processes will be explained below with reference to the drawings.

<Etching> FIGS. 2(a), 3(b) and 3 are cross-sectional views showing the selective etching process. First, as the substrate 2 to be processed, a second
As shown in Figure (a), a 5tO2 film 22 and an undoped poly 51m23 were formed on a Si grave 21.

As the gas introduced into the vacuum container 1, C12, which is an etching gas, was used. Furthermore, the emission wavelength of the light source 6 is 2
22 [nm], and the emission wavelength of the light source 12 was 308 [nm]. Here, the present inventors would like to discover the noteworthy experimental facts shown below, for example, Sekine, Okano, Horiike; Proceedings of the 5th Dry Process Symposium P97;
Tokyo, 1983). That is, the additive-free poly 3i film has CI2
Etching occurs only when the surface is directly irradiated with ultraviolet light, and this etching is accelerated by electron-
This fact is due to the generation of hole pairs. The second light 13 is within the optical absorption wavelength of CI2 molecules and photodissociates CI2 molecules very efficiently. On the other hand, the first light 7 having a shorter wavelength than this light passes through the optical system to the poly S1 film 23.
The image is reduced and projected onto the surface, forming a pattern consisting of a bright portion 24 and a dark milk portion 25 as shown in FIG. 2(b). Then, 3i is excited only in the bright portion 24, and electron-hole pairs are formed. Therefore, as is clear from the experimental facts described above, etching progresses only in the bright areas 24 and grooves are formed. Here, the reason why the first light 7 is selected to have a short wavelength is that the resolution of the pattern projected onto the poly S1 film 23 and the depth of focus of the optical system are each expressed by the following formula. This is because the shorter the wavelength of light used, the higher the resolution and the deeper the depth of focus can be obtained. Note that in the above equation, NA indicates the numerical aperture of the lens. Further, in the above example, the selective etching process described above is performed on the entire surface of the substrate 2 while moving the substrate 2 in a step-and-repeat manner.

In this way, by projecting a high-resolution pattern onto the substrate 2 to be processed and simultaneously irradiating the sample surface with the light 13 that dissociates CI2 molecules, damage-free and selective resistless etching can be achieved. Become. In this case, by appropriately selecting the wavelength of the first light 7, it is possible to make the selection ratio between the poly S1 film 23 and the underlying SiO2 film 22 infinite, and it is possible to It can become an indispensable etching technology in the modern era.

Moreover, FIG. 3 shows the case of etching N+ poly 3i to which phosphorus is added at a high concentration, and 31 in the figure is a 3i substrate;
32 is SiO2 discipline, 33 is N+ poly-Si with phosphorus addition.
It is a membrane. In this case, the two laser beams 7.13
In addition, an Ar + ion laser beam 36 of 253.7 [nm] is used from another light introduction window, and this beam 36
was irradiated parallel to the sample. Also, C as an introduced gas
S i (CHa ) 4 +HQ was added to I2. The laser beam 36 excites l-1, and due to this sensitizing effect, Si (CH3)4 is easily decomposed and becomes a polymer, which is deposited over the entire surface of the substrate 2 to be processed. On the other hand, in the bright portion 34, which is a light passage portion, the deposited film is removed by optical excitation, and etching progresses in the vertical direction. On the other hand, on the sidewalls, as with the dark portion 35, the inner surface of 3 is deposited and protected by the polymer, and as a result, a pattern conforming to the mask dimensions is selectively formed on the N+ poly-Si film 33. In addition,
The film deposited on the dark portion 35 and on the sidewalls of the pattern is
For example, it is easily dissolved in an organic solvent such as acetone, and its removal is extremely simple.

Deposition> FIGS. 4(a) and 4(b) are cross-sectional views showing the selective deposition process. First, as the substrate 2 to be processed, a SiO2 film 42 film 2 formed on a substrate 41 was used as shown in FIG. 4(a)k. The same wavelength of 25.3.7 nml was selected as the emission wavelength of the light sources 6 and 12. The gases introduced into the container 1 include W(Go)s and Cr(Go).
6. Carbonyl compounds such as Fe (GO)s and Cd
(CH3)2 , A I2 (C)I3)6 ,
A deposition gas consisting of a methyl compound such as S i (CI-13)4 was used. These deposition gases efficiently absorb the laser beam 13 from the light source 12 and photodecompose it to deposit metal. On the other hand, nuclei grow in the bright area 44 onto which the mask 10 is projected, and the subsequent film growth rate becomes significantly faster than in the dark area 45. Therefore, as shown in FIG. A thin metal film 46 will be selectively deposited.

In this case, as in the case of etching, nucleus growth can be confirmed even if the wavelength of the laser beam is selected to be shorter, and selective deposition of thin films with even finer patterns can be performed. Further, as the wavelength of the laser beam 7, for example, 193[nll] of ArF excimer laser beam or CO
2 laser beams 10.4j1. If a multi-photon excitation process using the [μm] band is used together with the substrate temperature raising effect of the laser beam 7, the deposition gas SiH++NO2, AI2 (
CH:l)s +NO2 etc. to 8102. Al2O3
It is also possible to selectively deposit insulating films such as .

Deposition→Etching> The fifth factors (a) and (b) are cross-sectional views showing a process in which the etching and deposition are successively performed in a self-aligned manner. As the substrate 2 to be processed, a single crystal 3 is used as shown in FIG.
Using the i-board 51, the emission wavelength of the first light 1116 is set to 22
2[nll], and the emission wavelength of the second light source 12 is set to 308[nll].
It was set as ll. As the introduced gas, CI2 gas, which is an etching gas, was first used. In this case, as in the case of etching described above, etching progresses only in the bright areas 54 projected by the mask 10, and the etching progresses only in the dark areas 55.
However, the etching did not proceed. Furthermore, the 3i board 5
The (100) plane of 1 was etched faster than the (111) plane. Therefore, the etched shape is a tapered shape in which the (111) plane appears on the side wall as shown in FIG. 5(a).

In this state, the emission wavelength of the first light source 6 was changed to 193 [nm] of ArF excimer laser, and 5IH40N20 was introduced as a deposition gas instead of CI2 gas. This results in the fifth
As shown in Figure (b), Sh is applied to the bright area 54, that is, the etched area.

2 discipline 56 will be embedded in the self line.

In this way, the portion 57 in which the active region of a transistor or the like is formed can be separated by a photoexcitation reaction without radiation damage, and it can be carried out using a self-alignment line, which is extremely effective in manufacturing ultra-fine semiconductor devices. be.

<Doping> FIG. 6 is a cross-sectional view showing a selective doping process of impurities. A $1 substrate 61 was used as the substrate 2 to be processed. 1st
The light source 6 is the same as in the previous etching case, and the second light source 12 is a multiphoton CO2 laser with a wavelength of 10°4 [μTrL], and the introduced gas is BCl3 containing P-type impurities. Using. In this case, the dark portion 65 on the 3i substrate 61 is not doped with impurities, but the bright portion 64, which is the light passage portion, is selectively doped with 8 (boron). This makes it possible to selectively form the P-type diffusion layer 66 on the 81 substrate 61. Note that by appropriately selecting the output of the laser beam 7, the depth of the scattering layer 66 can be controlled to be extremely thin. Therefore, it can be a promising technology as a future method for forming shallow junctions.

As detailed above, according to the present device, the photo-excited fluorescent light Fi5
Taizayotabetsu, Sodehan Tanuki Kagome 9 and 11. Selective etching, deposition, and non-irradiation damage can be achieved by using
Doping can be achieved. In addition to this, by combining the laser wavelength, output, introduced gas, etc., it is of course applicable to processes such as selective oxidation, nitriding, and direct development of resists. In this case, since there is no need to use a mask that is in close contact with the substrate 2 to be processed, various processing processes can be simplified, which is extremely effective for the formation of future ultra-fine elements.

Note that the present invention is not limited to the embodiments described above. For example, the first light source is not limited to a laser, but may also be a silane 70 as shown in FIG. 7. Furthermore, in the embodiment, a method has been described in which the entire surface of the sample is processed by moving the substrate to be processed using a step-and-repeat method, but the sample may be irradiated with light that is perpendicular to the sample all at once. In this case, since a large-area light-emitting surface is required, it is preferable to use the above-mentioned Hg lamp or the like. Furthermore, the second light source is for photodissociating the gas introduced into the vacuum container, and can be changed as appropriate as long as it can sufficiently dissociate the gas. Furthermore, it is also possible to provide a mechanism for heating the substrate to be processed to perform the various treatments more effectively.

Further, the etching gas is not limited to CI2, but any gas containing at least a halogen element may be used. Furthermore, the deposition gas may be any gas that contains a substance that is a raw material for the thin film to be deposited, and usually any gas that contains at least one of carbon and hydrogen. Further, the doping gas may be P type or N type.
Any gas containing type impurities may be used. Further, by applying the present invention to a series of VLSI manufacturing processes such as oxidation and doping, it is possible to manufacture VLSIs without using a resist mask.

In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a semiconductor surface treatment apparatus according to an embodiment of the present invention, and FIGS. 2 to 6 are for explaining the operation of the above-mentioned apparatus, respectively. FIG. 4 is a cross-sectional view showing the selective etching process; FIG. 4 is a cross-sectional view showing the selective deposition process; FIG. 5 is a cross-sectional view showing the process of performing selective deposition and selective etching in self-line; FIG. 6 is a cross-sectional view showing the selective doping process. 7 are main part configuration diagrams for explaining a modified example. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Substrate to be processed, 3... Susceptor, 4... Gas inlet, 5... Gas exhaust port, 6...
...first light source, 7...first light, 8...reflector,
9°...Focusing lens, 10...Mask, 11...
Focusing lens (light introduction window), 11'... Light introduction window, 12
...Second light source, 13...Second light, 14...Light introduction window, 15...Light guide window, 21°31.41.51
．． 61...3i board, 22,32°42...S+0
2 film, 23.33... Poly 3i film, 24.34.44
．． 54.64...Bright part, 25°35.45,5
5.65... Dark part, 46.56... Deposited film, 6
6... Diffusion layer. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

Scope of Claims: (1) A vacuum container for accommodating a substrate to be processed, a means for introducing gas into the container, a means for exhausting the gas in the container, and a vacuum container for accommodating a substrate to be processed; a first light source that irradiates light substantially perpendicularly to the processing surface; a mask that is disposed between the light source and the substrate to be processed, and has a desired pattern formed thereon consisting of a light passage portion and a light non-passage portion; The pattern on the mask is provided with an optical system that images the pattern on the substrate to be processed, and a second light source that irradiates light substantially parallel to the surface to be processed of the substrate to be processed. A surface treatment apparatus characterized in that light from the first light source is selectively irradiated onto the substrate to be treated according to a pattern. (2) The first light source and mask are provided outside the vacuum container, and the light that has passed through the mask exits through the light introduction window provided on the wall of the container. !
The surface treatment apparatus according to claim 1. (3) The light from the first light source that passes through the mask is irradiated onto the substrate to be processed all at once or irradiated locally, and the substrate to be processed is moved in the X and Y directions. A surface treatment apparatus according to claim 1, characterized in that: (4) The surface treatment apparatus according to claim 1, wherein the light from the first light source that passes through the mask has a wavelength from an ultraviolet region to an X-ray region. (5) The second light source is provided outside the vacuum container, and the light from this light source is introduced into the container through a light introduction window provided on the wall of the container. A surface treatment apparatus according to claim 1 or 2, characterized in that: (6) The surface according to claim 1, wherein the light from the second light source that passes in parallel over the substrate to be processed is sheet-like and wider than the major axis of the substrate to be processed. Processing apparatus. (7) The light from the second light source that passes in parallel over the substrate to be processed is composed of two or more types of light having mutually different wavelengths. The surface treatment apparatus according to item 1. (8) The light from the first light source that passes through the mask and the light from the second light source that passes in parallel over the substrate to be processed have different wavelengths. The surface treatment apparatus according to claim 1, characterized in that: (9) the light from the second light source that passes in parallel over the substrate to be treated is at least connected to the gas introduced into the container; The surface treatment device according to claim 1, characterized in that the surface treatment device has a wavelength within an absorption band of Claims characterized in that the optical system for imaging is made of a material transparent to light from the ultraviolet region to the X-ray region, such as fused silica, high-purity alumina single crystal, and lithium fluoride. The surface treatment apparatus according to claim 1. (11) The surface treatment apparatus according to claim 1, further comprising means for heating the substrate to be treated. (12) Inside the vacuum container. The surface treatment apparatus according to claim 1, wherein the gas introduced into the surface treatment apparatus is a deposition gas containing at least one of carbon and hydrogen, and a thin film is selectively deposited on the substrate to be treated. (13) The method according to claim 1, wherein the gas introduced into the vacuum container is an etching gas containing a halogen element, and the substrate to be processed is selectively etched. Surface treatment apparatus. (14) A patent claim characterized in that the gas introduced into the vacuum container is a doping gas containing P-type or N-type impurities, and the substrate to be treated is selectively doped with impurities. The surface treatment device according to item 1.