JPS61296723A - Surface treatment apparatus - Google Patents

Abstract

PURPOSE:To remove a damaged layer of an Si substrate and eliminate remaining reactive gas molecules and atoms from the surface of the Si substrate by etching the damaged layer at the low temperature about 400 deg.C and with good controllability. CONSTITUTION:A treatment gas is introduced into an evacuated vacuum apparatus while being evacuated. High power ultraviolet rays are applied to an Si substrate placed on a target and a damaged layer is etched. After the etching is completed, introduction of the treatment gas is discontinued and, while being evacuated to the high vacuum rate again, UV application only is performed to elevate the substrate temperature. In other words, halogen molecules and atoms adsorbed by the Si surface layer are dissociated under the elevated temperature and decreased pressure while the lights are being applied so as to make adsorbed atoms or molecules not to remain on the Si surface layer at all.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface treatment apparatus used in an electronic device manufacturing process using Si.

(Prior art and its problems) When 5 int is etched by reactive sputter etching, a layer containing carbon and halogen atoms is formed on the underlying S1 layer. Conventionally, in order to remove carbon and halogen, 200 to 300 oxidation methods (Ht:O, = 1:1 wet
A method was used in which the oxide film was removed using hydrofluoric acid (Eiji Iyo et al., 30th Japan Society of Applied Physics Association Conference, P310, 6a-V-10). The conventional method requires high-temperature treatment at about 950° C., which may change the impurity distribution required for the device.

The thickness of the oxide layer also varied depending on the degree of carbon incorporation, making it difficult to control.

Another method, as described above, is to etch the damaged layer by wet or dry etching instead of oxidizing and removing it. In the case of wet etching, I (No. 3
．． A diluted PIF is used, but the etching rate is extremely high (3000 to 4000/-), and keeping it low and controlling it is more difficult than controlling the oxide film thickness.Also, dry etching The method of etching the surface layer by etching involves the incidence of ions and physical damage cannot be avoided.At the same time, chlorine,
Fluorine atoms and molecules are incorporated and require subsequent annealing. That is, the halogen atoms and molecules in the gas used for the treatment cannot be removed, and in the end, even if carbon can be removed by removing the surface layer by etching, the halogen atoms remain.

Therefore, the purpose of the present invention is to eliminate these conventional drawbacks,
Provides a processing device that can remove damaged layers by etching the Si substrate at a low temperature of about 400°C with good controllability in surface processing of Si substrates, and does not leave any reactive gas molecules or atoms used in the processing on the Si substrate. It's about doing.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a surface treatment apparatus that processes the surface of the Si substrate by placing the Si substrate on a target in a vacuum apparatus. , means for heating the target to adjust the temperature of the substrate, means for irradiating the Si substrate with ultraviolet rays, chlorine gas, fluorine gas, and XeF.

A gas introducing means for selecting a gas or a mixture thereof and introducing it into the vacuum device, and a means for adjusting the degree of vacuum in the vacuum device, the temperature and the degree of vacuum being within a predetermined range. In some cases, the gas introducing means starts introducing the gas, and after a predetermined time has elapsed from the start of introducing the gas, the ultraviolet irradiation means starts irradiating the ultraviolet rays, and a predetermined period of time elapses from the start of the ultraviolet irradiation. After a lapse of time, the gas introduction means finishes introducing the gas, and after the gas introduction ends, the temperature adjustment means makes the temperature of the substrate constant or increases, and the vacuum degree adjustment means adjusts the degree of vacuum. In addition, the ultraviolet irradiation means may finish irradiating the ultraviolet rays after a predetermined time has elapsed from the end of the gas introduction.

(Operation) The present invention solves the problems of the prior art by the above-mentioned means. That is, a processing gas is introduced into a sufficiently evacuated vacuum apparatus while being evacuated, and high-power ultraviolet light is irradiated onto the Sl placed on the target to etch the damaged layer. After etching is completed, the processing gas is stopped, and while evacuation is again performed to a high degree of vacuum, only light irradiation is performed to raise the substrate temperature. That is, the nine-rogen molecules and atoms adsorbed on the Si surface layer are irradiated with light and then desorbed under elevated temperature and reduced pressure so that no adsorbed atoms or molecules remain on the Si surface layer.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a diagram showing the configuration of an embodiment of the present invention. In this embodiment, a target 18 with a built-in heater is provided in the vacuum chamber 11, and a sample 19 is placed on the target 18. Further, on the vacuum chamber/bar 11, there is an ultraviolet light transmitting window 17 through which light emitted from an ultraviolet light source 120 can pass. A mercury lamp of 800 mW/α2 was used as the light source 120. As a vacuum evacuation system, a turbo molecular pump 13. There is a rotary pump 14 that can exhaust to a high vacuum. On the other hand, chlorine, fluorine gas, etc. are selected and introduced into the vacuum chamber/bar 11 through the gas inlet 16 . Furthermore, when introducing gas, there is a port for evacuation, −
The tally pump 14 is connected to the vacuum chamber 11 via a variable conductance pulp 15. In this embodiment, a turbo molecular pump 1 is used for high vacuum pumping.
3 was used, but an oil diffusion pump or cryopump can also be used. However, with oil diffusion pumps, sample contamination by oil became a problem even when a cold trap was used. Furthermore, the rotary pump 14 was even more effective when used in combination with a mechanical booster bomb. The temperature of the target with a built-in heater can be changed by a controller, and in this example, a target that can be raised to 500°C was used.

Next, 5102 was etched with CF4+ using a parallel plate type etching device.
H, (200W, 0.18 W/c!IL') at 1μ
M etching, over etching for 2 minutes, and base S
An example in which surface treatment was applied to a sample damaged by Sample No. 1 will be described below.

FIG. 2 shows an example of the sequence of surface treatment according to this embodiment. FIG. 2(a) shows the opening and closing of the shutter, (b) shows the exhaust method, (C) shows the gas inlet, and FIG. 2(d) shows the change in target temperature. Furthermore, roughly speaking, the surface treatment process according to this embodiment can be divided into four areas on the time axis. In the first region A, the sample is evacuated to a high vacuum by the turbo molecular pump 13, that is, the sample is placed at about 10-' TOLL. At this time, the shutter is closed and the gas inlet 16 is also closed.

On the other hand, the target temperature is raised to a certain level in preparation for the next temperature rise in region B. Although this is not essential to the apparatus of the present invention, it was necessary to reduce the processing time to a single hour. The temperature T1 at this time was 180°C. Next, in the second region B, the exhaust gas is switched from the turbo molecular pump 13 to the rotary pump 14, and at the same time, the gas inlet 16 is opened and XeF is introduced. It is also better to raise the substrate temperature at this point in order to shorten the processing time. The temperature at this time was approximately 250°C. Then, when the gas pressure is maintained at a constant level, the third
Enter area C and open the shutter.

At this point, etching begins. Then, when the predetermined etching is completed, the fourth region DK water pump 4 is switched to the turbo molecular pump 13. In this etching reaction, fluorine radicals react with the Si substrate to form SiF. Further, the target temperature is increased from 250°C to 350°C (=Ts). That is, the temperature is raised in a high vacuum while irradiating light. Then, the fluorine atoms adsorbed on the sample surface are easily desorbed because the temperature is raised, the sample is in a high vacuum, and it is irradiated with ultraviolet rays.

In this processing example, area A is 1 minute, area B is 10 seconds, area C is
was 1 minute, and the area was 1 minute. These processing times are
Although it varies depending on the temperature of the target 18, if the temperature is 500° C. or higher, it loses its meaning as a low-temperature process, and problems such as redistribution of impurities occur. In addition, the light source 120 has a power of 10 to 30''/'cm, which is too low for a normal mercury lamp, and the processing time becomes long.
A high output type of 0 mW/cm' was used. The apparatus of this embodiment is capable of irradiating up to 5 inches with a single wafer of 4 inches. Patch processing is also possible by combining a large number of these light sources.

Figure 3(a) shows the MA spectrum immediately after etching of Sl, which was over-etched for 2 minutes after etching Si0° using a parallel plate type etching device.
) shows the -1 MA spectrum of day 1 immediately after etching 300 people using the example shown in Figure 1, but before processing it shows the -1 MA spectrum of about 3
(Although carbon atoms and fluorine atoms are mixed in from the Si surface layer, after the treatment in this example, carbon atoms and fluorine atoms were below the detection limit. Furthermore, even when examined by Aussie analysis, dry It was at the same level as the Si surface before etching.

(Effects of the Invention) As shown above, the surface treatment apparatus of the present invention has 400
The damaged layer can be etched and removed with good control at a low temperature of around 0.9°C. Therefore, by using this surface treatment equipment,
Removes layers containing carbon, fluorine, etc. after dry etching, leaving no problems in subsequent processes. That is,
Problems such as poor contact will also be eliminated. Furthermore, since gas molecules and atoms used in the treatment do not remain on the surface, there is no need for annealing or the like due to the high temperature process. This means that the shape of impurity distribution, which is important for semiconductor processing, does not change. Therefore, the influence of the present invention on the surface treatment step of semiconductor processing is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 2 (J
L) to (d) are diagrams showing processing steps according to the embodiment in FIG.
Figure 3 (a) is a diagram showing the MA spectrum of Sl that was over-etched for 2 minutes after Si 0° etching using a parallel plate type etch device, and Figure 3 (b) is a diagram showing the MA spectrum of Sl that was etched by 300 people using the example shown in Figure 1. It is a figure showing an IMA spectrum. 11... Vacuum chamber, 12... Gate pulp,
13...Turbo molecular pump, 14...Rotary pump, 15...Co/ductor/s variable valve,
16... Gas inlet, 17... Ultraviolet light transmission window, 18
... Target with built-in heater, 19 ... Sample, 12
0...Light source. Agent Patent Attorney Shin Honjo Valve tube 2 drawing dS3 drawing (a) C1100200300 S1 middle Oj kusa (λ)

Claims (1)

[Claims] Place the Si substrate on a target in a vacuum device and
An apparatus for treating the surface of a substrate, comprising means for heating the target to adjust the temperature of the substrate, means for irradiating the Si substrate with ultraviolet rays, chlorine gas, fluorine gas,
A gas introducing means for selecting XeF_2 gas or a mixture thereof and introducing it into the vacuum device, and a means for adjusting the degree of vacuum in the vacuum device are provided, so that the temperature and the degree of vacuum are within a predetermined range. At a certain time, the gas introducing means starts introducing the gas, and after a predetermined time has elapsed from the start of introducing the gas, the ultraviolet ray irradiation means starts irradiating the ultraviolet rays, and from the start of the ultraviolet irradiation. After a predetermined time has elapsed, the gas introduction means ends the introduction of the gas,
After the gas introduction is completed, the temperature adjustment means maintains or increases the temperature of the substrate, and the vacuum degree adjustment means increases the degree of vacuum, and after a predetermined time has elapsed from the end of the gas introduction, the ultraviolet irradiation means A surface treatment device characterized in that the irradiation with the ultraviolet rays is finished.