JPS5925223A - Method for cleaning of substrate and device therefor - Google Patents

Abstract

PURPOSE:To improve the resist adhesive property even when a low-temperature prebaking treatment is performed at 70 deg.C or thereabout and to enable to perform a resist coating process at a low temperature by a method wherein a substrate is cleaned by exposing its surface to neutral oxygen excitation atoms. CONSTITUTION:The substrate 5 is placed on a conveyer belt 21. Oxygen or oxygencontaining gas is led from a gas introducing hole 3. A low pressure mercury-arc lamp 1 irradiates ultraviolet rays having the wavelength of 184.9nm and 254.7nm respectively on the substrate 5. Oxygen is converted to ozone gas by performing an ultraviolet irradiating process, the formed ozone gas is decomposed by ultraviolet rays, and an oxygen radical having very strong oxidizing force is formed. Said oxygen radical remove by oxidizing and decomposing the attracted contamination layer on the surface of the substrate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate cleaning method and a substrate cleaning apparatus necessary for forming a desired layer/stopper on a substrate made of Sl or an Sl compound, and in particular to a semiconductor integrated circuit device, The present invention relates to a substrate cleaning method and a substrate cleaning apparatus suitable for forming a desired pattern/stop pattern on an 81 series substrate such as a Josephnon integrated circuit device.

First, the current state of the technology will be outlined below.

When a resist film is formed by applying an electron beam resist such as a positive photoresist consisting of a resol novolac resin and a quinone sia 7F compound to a substrate having a surface of a Sl or 8i compound, the difference between the substrate and the resist film is Immediately before applying the resist film, apply Hegizamethyldi/Raza/(11N=I
A method of applying an organic lantern solution such as I)S) is widely used. Regarding this, it is known that 011 groups are usually adsorbed on the surface of the Si compound, and the adhesion of the Rennost film to the substrate surface on which such an adsorption layer exists is extremely poor. . Therefore,
By applying IIML)S to the surface of the substrate on which such an adsorption layer exists and heating it, the following formula (1) is obtained on the surface of the 81 substrate.

2si-OIl+(Si (Cll!,), ], Nl
l→2si −, o-Si (ell) 10N
l13↑ ・ (1) 3 rows), i, , jμ rows, -8 on the surface of the substrate;
(Cl13).

A reaction layer consisting of The profit margin between the S1 substrate surface on which such a reaction layer is formed and the above-mentioned resist film (JJ is extremely good, and as a result, the resist film has extremely good adhesion to the surface of the SI substrate). However, in order to form a strong reaction layer, i
f lν11) It is necessary to perform heat treatment after S coating. If this reaction layer is insufficient, it will not be possible to obtain lennost adhesion that is sufficient for practical use.
Generally, IIN=II) is carried out subsequent to S coating, and is often substituted by pre-bake treatment after S coating. .

Table 1 Table 1 shows the Si0 vapor deposited film, S1 crystal, and thermally oxidized S
After applying 4DS to each substrate of 102 films, AZ
- 1470 resist (7 Nobley product name) 1, 1
The coating was applied to a thickness of μI'11, and then further heated in a convection Haake oven.
After pre-baking for 0 minutes at each temperature between 70 and 90 degrees Celsius, the pattern was printed using Toshika's light exposure method, and then developed for about 2 minutes in an AZ developer diluted twice with pure water. Based on the presence or absence and degree of disappearance of the stain/stripe pattern, the stickiness of the stain/strike is determined/results are shown.

From the results in Table 1, for all three types of 81-based substrates, a pre-bake treatment at a temperature of 85 to 90°C is necessary to obtain extremely good stickiness without loss of the pattern. I understand that it is. However, when the photosensitive agent contained in the resist material is heated above 90 DEG C., a thermal splitting angle occurs, resulting in a low resist sensitivity. In fact, when manufacturing integrated circuits made of lead alloys, it is necessary to process them at as low a temperature as possible due to the heat resistance of the lead alloy. The upper limit is limited to 70°C.

However, as is clear from Table 1 of QJ1, pre-baking at a temperature of 70°C and 1°C resulted in an insufficient resist film (=1 adhesion), resulting in these S1-based substrates Since it is extremely difficult to obtain exactly the desired coating/stripping pattern, there has been a strong demand for the development of a new resist coating force method.

SUMMARY OF THE INVENTION In response to the above-mentioned needs, an object of the present invention is to provide a novel substrate cleaning method that eliminates the drawbacks of the prior art, that is, to obtain a resist film with sufficient adhesion even during pre-baking at a low temperature of about 70°C. Our goal is to provide that device.

A characteristic feature of the substrate cleaning method of the present invention, which achieves the purpose of item 1, is that it includes a step of exposing the substrate surface to neutral oxygen excited atoms, and a characteristic of the substrate cleaning apparatus of the present invention. where the wavelength is 195n+n
The oxygen trench includes an ultraviolet lamp that simultaneously emits ultraviolet light with a wavelength of 240 to 260 on, and a hole for introducing a mixture of oxygen and inert gas.

In the above, the step of exposing the substrate surface to neutral oxygen excited atoms is carried out in air or in an oxygen atmosphere with a wavelength of 1 8 4
．． 9 111n and wavelength 254. A process may be used in which the surface of the substrate is irradiated with a low-pressure mercury lamp that emits ultraviolet rays of 7 nm, or the oxygen excitation source r- in the oxygen -JJ Snosismer produced by applying high-frequency power to an oxygen atmosphere under reduced pressure may be applied to the substrate. Even the process of irradiating the surface is dangerous.

In the above, the surface of the substrate is made of Si-47, and the surface of the Si compound substrate is subjected to the process of exposing the surface of the VC substrate to the neutral oxygen excitable source r-. It goes without saying that a method comprising the steps of applying hexamethyl/nraza/ on the surface of the substrate and further applying a resist film is also an example of non-invention and falls within the scope of the present invention.

According to the present invention, the present invention can be applied to a temperature below 1°F, which is extremely good even in the low-temperature rinsing process of about 70°C. Please refer to this for a more detailed explanation.

FIG. 1 is a side cross-sectional explanatory view of a substrate cleaning apparatus according to an embodiment of the present invention.

1, numerals 1.1, . . . are a group of uninvented low-pressure mercury lamps for cleaning substrates, 21 and 22 are wafer conveyor belts, 6 is an introduction hole for oxygen extraction or a gas containing oxygen; 4 is a gas exhaust hole, 5 is a wafer, 6 is a wafer chuck of a resist spinner, 7 is a droplet F hole for hexamethyldi/lasane (111VII) S), 8 is a droplet/sl-
A liquid dripping hole, 9 a wafer/unloading section, and 10 a wafer storage section.

Referring to Fig. 1, the low-pressure mercury lamp group 1.1, .
It consists of 4 sets of lamps, and the distance from the center of the lamps to the surface of the lamp is approximately 1511) In. When oxygen sludge is supplied from the sludge introduction hole 6 at a flow rate of 1017 m i n , the ultraviolet intensity on the wafer 7 and 50 surfaces was measured, and the emission line at wavelength 184 and 9 nm was approximately 5001 tW/cm2, and wavelength 253 and 711111 tW/cm2.
The emission line is about 10μW/C1112, and in this case the ozone concentration near Ueno is 70~1001
Month 11 Deatsu/ko.

The wafer set in the wafer unloading section 9 is transferred to the conveyor belt 2.
1, and ultraviolet irradiation is performed in the presence of ozone gas using an uninvented substrate cleaning method. The ultraviolet irradiation time is adjusted by adjusting the conveyance speed of the conveyor belt 21. Following the ultraviolet irradiation treatment, the wafer is placed on the wafer chip 6 of the resist spinner.
Move 111\I l) II from S Swamp 11/hole 7
By dropping MI)S onto the substrate and rotating the chuck at the same time,
) After spin-coating S, apply 1 drop of resist solution.
A resist solution is dropped from the hole 8, and a resist film is applied by rotation in the same manner.Finally, the wafer is stored in the wafer unloading section 10 by the wafer conveyor 22, and step d is completed.

In the following, an embodiment of a coating method using a coating apparatus to which the substrate cleaning method of the present invention is applied will be described in detail in 1.--.

It should be noted that in the following plan 1-5, we will also describe a comparison test that is not based on the present invention, and we will demonstrate the effects of the present invention in this comparison.

The surface of the substrate was immersed in a mixture of concentrated sulfuric acid and 1lFfi hydrogen oxide for about 10 minutes, then washed in pure water and dried. 13K)
Ultrasonic cleaning in acetone for about 20 minutes followed by rinsing with fresh M 113 K and drying; Ultrasonic cleaning in acetone for about 20 minutes followed by rinsing in fresh acetone and then ethanol and drying; Two sets of substrates were each prepared without being subjected to substrate cleaning treatment.

For one set, the surface of the substrate was irradiated with ultraviolet rays for about 1 minute using an ultraviolet irradiation device to which the substrate cleaning method of the present invention was applied, and then hexamethylzine lazan (1-
IMD8) was spin coated at 20 []0 strokes 11) for about 10 seconds. Furthermore, AZ-1470/strike (/
Nobley Co., Ltd. (trade name) was spin-coated at 5000 rpm for about 20 seconds. Subsequently, a pre-hake treatment was performed for 50 minutes in a convection oven heated to 70°C. As a result, the resist coating process including the substrate cleaning process according to the present invention is completed, and the coating film thickness is 1.1 μm! ]] of]AZ
-1470 resist was obtained.

Unfortunately, the other set of substrates was used as a comparative example that is not based on the present invention, and this set of substrates was treated with the above-mentioned substrate cleaning method using ultraviolet irradiation in the same manner as in the conventional laser/spray coating process. ... processing? Immediately after the S coating treatment/
Stret coating process, °, same treatment conditions as above - Strip A11:
I went to FC-U.

Test battens were transferred onto these two sets of substrates that had undergone the coating process using a normal light exposure method, and A7. Developed for 2 minutes in a developer (1.1 diluted solution) ('i: L, washed with water and dried).

By observing the appearance of the thus formed resist film using a microscope, the adhesion of the resist film to 471 can be evaluated. In other words, if the stickiness 17I: is orange and good, there will be an isolated bump size of 17zl11 or less without being washed away from the substrate, whereas if the stickiness is poor, the size is r soil, the size is 1Q. 777 of ノ++n or more
It separates from the board and is washed away at a moment's notice.

Based on these observation results, we set the adhesion properties to four levels under outdoor lighting, and determined the adhesion properties of each substrate and its cleaning method as described above.
And substrate pretreatment for substrate cleaning/grinding by ultraviolet irradiation! Table 2 shows the evaluation results for each test with and without lj.

Table 2 As shown in Table 2, the conventional coating process, which does not involve cleaning the substrate by ultraviolet irradiation,
Resist margins were classified as poor to good, while those that underwent substrate pretreatment of ultraviolet irradiation, which is the substrate cleaning process of the present invention, were all classified as ``extremely good'' and ranked as ``second class''. It is clear that the ultraviolet irradiation treatment according to the substrate cleaning method of the present invention has a remarkable effect on improving the profit margin condition of Regime 1.

Table 6 shows the results of investigating the effect of substrate pretreatment time of ultraviolet irradiation using the substrate cream method of the present invention on SiO film substrates, and the processing conditions and evaluation methods are shown in Table 2. The same is true for .

From the results in Table 5, it is clear that the UV irradiation treatment according to the present invention for about 15 seconds significantly improved adhesion. It is.

As shown in Table 2 and Table 0 and 0, the reason why the resist adhesiveness is significantly improved by ultraviolet irradiation treatment according to the substrate cleaning method of the present invention before application of IIMI)S is as stated. That is, on the surface of the substrate, there is usually a monomolecular layer containing small hydrocarbons as the main component ~ number 5) 7
There is a layer of adsorption contamination. This adsorption 7ri dye layer is made up of resist residues ＼ and anti-a liquid 4 remaining from the previous treatment process.
It inevitably occurs due to adsorption from the air. If an adsorbed contamination layer such as tl M I) exists on the surface of the S+ series substrate, in order for the reaction shown in the above chemical reaction formula (1) to proceed sufficiently by applying S,
It is clear from the results shown in Table 1 that heat treatment at a temperature of 85 to 90°C is necessary.

However, due to the substrate cleaning method of the present invention, that is, ultraviolet irradiation treatment, oxygen in the atmosphere is changed to ozone gas, and the ozone gas generated is further decomposed by ultraviolet rays, producing oxygen radicals with extremely strong oxidizing power. As a result, the adsorbed contamination layer mainly composed of hydrocarbons on the substrate surface is oxidized and decomposed into CO2 and 1120 by oxygen radicals and removed, exposing the genuine Si-based surface without any contamination layer. If you do so, it will be judged as having become sharp.

As a result, the subsequently applied l-I M ]) S and S
The reaction with the l-based surface becomes extremely easy, and the results shown in Table 2 and 6
As shown in the table, only by heat treatment at 70°C for 60 minutes, a necessary and sufficient chemical reaction between II'VI D S and the Sl-based surface proceeds, resulting in good resist adhesion. It is something that can be done.

In addition, the present invention-1, IIMI-)S or other resists effective as adhesives, such as cresol novolac type photoresist 11, +11M MA and I''13M etc., methacrylate-1 type resist 1-1/ Even in this case, it is clear that a Fi1-like effect can be expected as shown in this example.

As explained above, the present invention has a low r7+ temperature of about 70°C! As a result of being able to obtain a very good t-brihake treatment odor-C, it became possible to obtain a very good /stoy-1 p+, resulting in a low /1 odor or i-1 performance in the c/sto coating process, and as a result: 11 ③/Josephson integration l] A wide range of manufacturing yields of 11 was achieved.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional explanatory view for explaining the principle of a 7-stroke coating II device equipped with a board cleaning device, which is an embodiment of the present invention. 1.1 Low-pressure mercury slurry ' nY Filter Oxygen sauce 1, introduction hole 4 for gas containing oxygen Gas J
ll Pore 5...Wafer 6 U...Dating 7...II~IDS dripping hole 8 Shi/St IMI
IL 9・Wafer unloading section 10・Wafer storage section 21.22・・Transfer belt Patent applicant
Junnosuke Nakatoshi, patent attorney representing Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] (I It' (i) A substrate cleaning method characterized by comprising a step of exposing the substrate surface to excited oxygen atoms. The substrate surface is not exposed to the excited oxygen atoms.
Wavelength 184, 9111n and wavelength 254.7n in surrounding air
A substrate cleaning method according to claim 1 in which the substrate surface is cleaned with a low water consumption lamp that emits ultraviolet rays of 0. The first step of exposing the substrate surface to the oxygen excited atoms is to irradiate the substrate surface with oxygen excited atoms -r in the oxygen gas Zolamasmer generated by applying high-frequency power to the oxygen atmosphere under reduced pressure. 1. A method of cleaning a substrate according to claim 1, which is a process. (4) After applying the step of exposing the substrate surface to the neutral oxygen-excited atoms on the surface of the 5i-J SI compound substrate, Apply hexamethyldi/lasan to the
A substrate cleaning method according to any one of claims 1 to 7, which comprises the step of applying a strike film. (5) Wavelength 195 old] Within 1 and wavelength 240-260 rule 1
1. A substrate cleaning device comprising: an ultraviolet lamp that simultaneously emits ultraviolet rays; and an oxygen exchanger or a mixed gas introduction hole of oxygen and an inert gas.