JPS6114724A - Irradiation of semiconductor wafer by ultraviolet ray - Google Patents

Abstract

PURPOSE:To enable to heat a high temperature in baking process by a method wherein a mercury-vapor lamp is irradiated at the first lighting state when the said lamp is lighted under the condition that U365/U254 value is smaller than one a half and then the said lamp is irradiated at the second lighting state when the above value is larger than three second. CONSTITUTION:Input electric power is descended about one tenth of rated electric power. As the result, an ultraviolet lamp 4 is worked as a low-pressure mercury lamp and is lighted under the condition that U365/U254 value is smaller than one a half. By this fact, the surface section of a pattern which is formed on the surface of a semiconductor wafer 6 is cured. Thereafter, when curing of the surface of formed pattern is accomplished, input electric power is raised up to the rated electric power and local cooling of a valve section, which surrounds an electrode section, is weakened. As a result, the ultraviolet lamp 4 works as a high-pressure mercury lamp as the same way as the design, and lights under the condition that U365/U254 value is larger than three second. By this fact, curing to the inside of formed pattern is accomplished for the short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for irradiating semiconductor wafers with ultraviolet rays.

In the semiconductor manufacturing process, ultraviolet irradiation is used to form oxide films, nitride films, metal films, etc. on substrates by photochemical vapor deposition, and to decompose and clean organic contaminants attached to the surface as a preliminary cleaning. It is used, but recently L
The application of SI to the baking process is attracting attention.

After this baking process, an oxide film etc. is deposited, and then there is a photosensitive process in which the semiconductor wafer coated with a photosensitizer is exposed to light to partially remove the photosensitizer, and the areas where this photosensitizer has been removed are removed. During the etching step, which removes the oxide film etc. of the etching film and forms a pattern, an etching process of 120 to 200
This refers to the step of baking at a temperature of about 0.degree. C., and higher temperatures are preferred because the adhesive strength improves. However, if this temperature is set to 140° C. or higher, the surface and vertical planes of the photosensitive agent become distorted, resulting in poor shape of the formed pattern, resulting in a problem that the LST performance deteriorates. Also, the hardness of the formed pattern is insufficient! However, in the etching process, this formed pattern is also polished and reduced in weight7, resulting in a decrease in performance. Therefore, if the semiconductor wafer is irradiated with ultraviolet light before the baking process, the formed pattern will be hardened, the pattern will not be distorted even if the heating temperature is 140°C or higher in the baking process, and it will not lose weight during the etching process. It is known.

By the way, in order to make this effect sufficient, the formed pattern must be sufficiently hardened not only on the surface but also on the inside thereof. During irradiation with ultraviolet rays, care must be taken to ensure that the formed pattern is not deformed 17 by the heat of the ultraviolet lamp or deteriorated due to the ultraviolet rays. Conventionally, low-pressure mercury lamps and high-pressure mercury lamps are well known as ultraviolet lamps. Among these, low-pressure mercury lamps mainly irradiate ultraviolet rays with a wavelength of 254 nm, but because the wavelength is short, the transmittance is low, and even if the surface of the formed pattern is hardened, the internal hardening is insufficient. . On the other hand, high-pressure mercury lamps emit ultraviolet rays with long wavelengths such as 305° and 310.565 nm, so they are convenient for curing the inside. causing deformation, and
It is also known that when an uncured pattern is irradiated with ultraviolet rays of 365 nm, minute bubbles of nitrogen and gas erupt on the surface, resulting in deterioration.

Therefore, the present invention is a semiconductor wafer that can be cured to the inside of the formed pattern, does not cause thermal deformation or deterioration, can be heated to a high temperature in the baking process, and does not lose weight even in the etching process. The purpose of the present invention is to provide an ultraviolet irradiation method. The configuration is that a mercury lamp designed to be used as a high-pressure mercury lamp is used to emit ultraviolet light with a wavelength of 365 nm (11t U345).
+254 nm ultraviolet light emission amount fU2sa, a step of irradiating a semiconductor wafer as an object to be irradiated in a first lighting state in which the value of U56VU254 is smaller than 1/2; f IJ”5/U
The method is characterized in that it includes the step of irradiating the irradiated object in a second lighting state in which the light is turned on in a state where the value of 254 is extremely large.

Embodiments of the present invention will be specifically described below based on the drawings.

The main mirror 2 of the equipment box 1 is placed horizontally in the center of the V.
Below the periphery, a vertical sub-mirror 3 is electrically distributed to form a box shape. In the empty space surrounded by this mirror 2゜3,
Straight tube-shaped ultraviolet lamps 4 are arranged side by side to form a substantially square surface light source, and the ultraviolet lamps 4 have an arc length of 20 crn and a rated power of 1000 W, and are designed to be used as high-pressure mercury lamps. It is a mercury lamp. Then, when the rated power is input, 305.310.36
Ultraviolet rays with long wavelengths of 5 nm are mainly generated, but ultraviolet rays with long wavelengths of 3 nm
65nm light emission 11Us6s and 254nnLD light emission amount U
The value of the ratio U''5/U254 is larger than the average value.

A front glass 5 made of quartz glass and having a rectangular shape of about 200 cm on a side is provided below the ultraviolet lamp 4, and the ultraviolet rays from the ultraviolet lamp 4 are transmitted through the front glass 5f and irradiated downward. A semiconductor wafer, which is the object to be irradiated 6, has a diameter of 6 inches (approximately 155 cm) and is supported by a support (not shown) at a distance of 2.5 efR from the ultraviolet lamp. A cooling fan 7 is installed on the side of the device box 1 to cool the ultraviolet lamp 4 and the mirror 2.31. In particular, by increasing the cooling air volume, the bulb section surrounding the electrode section of the ultraviolet lamp 4 is strongly cooled down, causing the temperature of that section to drop. It can be adjusted to 20-40°C. As a result, mercury particles accumulate inside the lamp, allowing it to operate as a low-pressure mercury lamp by lowering the input power.

Then, the semiconductor wafer that has undergone the exposure process is supported in the above-mentioned position, and the ultraviolet lamp 4 is energized to warm up the wafer. When this is completed, the cooling fan 7f is activated (and the input power is reduced to the rated level). As a result, although the book was designed to be used with four ultraviolet lamps and a high-pressure mercury lamp, it operated as a low-pressure mercury lamp, and the value of Usas7U25.
Lights up in a smaller state. Therefore, the wavelength is 254 nm.
The semiconductor wafer is strongly irradiated with ultraviolet rays, but this ultraviolet ray has a short wavelength and has low transparency, so it hardens the surface portion of the pattern formed on the surface of the semiconductor wafer.

Next, when the surface hardening of the formed pattern is completed, the input power is increased to the rated value, and the local cooling of the valve section surrounding the electrode section f is also weakened. As a result, the four ultraviolet lamps operate as a high-pressure mercury lamp as designed, and the U 545/,
Lights up when the value of zs, 4 is 6/2 or higher. For this reason, the semiconductor wafer is strongly irradiated with ultraviolet rays having long wavelengths such as 305, 310, and 365 nm, but these ultraviolet rays have high transparency and harden the inside of the formed pattern in a short time. In addition, as in the past, when irradiating an uncured pattern with a high-pressure mercury lamp, there were problems such as thermal deformation due to the heat generated by the lamp, and deterioration due to the eruption of fine N and gas bubbles on the surface. In the invention, the surface is first hardened, so these problems do not occur.
It can be hardened to the inside.

Next, the semiconductor wafer, which has been hardened to the inside of the formed pattern in this irradiation process, is baked at a temperature of 200°C,
The pattern was completed by plasma etching, and even though the baking temperature was as high as 200°C, a pattern with small distortion could be obtained uniformly over a wide area, and the pattern remained unchanged during the etching process. L S with excellent performance with almost no reduction in TL
It becomes possible to manufacture T.

As explained above, the present invention uses a mercury lamp as 0565/0565/
Irradiation is performed in the first lighting state where the value of U254 is smaller than 1/2, and then this value is 6. Since the irradiation is performed in the second lighting state in which the light is turned on in a state larger than /2, it can be cured within the formed pattern, and no thermal deformation or alteration will occur at that time. Therefore, according to the present invention, high m heating is possible in the baking process, and the adhesive strength is improved17.
It is possible to provide a method of irradiating ultraviolet rays onto a semiconductor wafer in which the pattern is not reduced even during the etching process.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of an apparatus used in an embodiment of the present invention, and FIG. 2 is a side sectional view thereof. 1... Equipment box 2... Main mirror 3... Secondary mirror 4... Ultraviolet lamp 5... Front glass 6... Irradiated object (semiconductor wafer 1-) 7... Cooling fan No. Figure 1 Figure 2

Claims (1)

[Claims] The amount of ultraviolet light emitted by a mercury lamp designed to be used as a high-pressure mercury lamp with a wavelength of 365 nm is U_3_6_5.
, a step of irradiating a semiconductor wafer, which is an object to be irradiated, in a first lighting state in which the light is turned on in a state where the value of U_3_6_5/U_2_5_4 is smaller than 1/2, when the amount of ultraviolet light emission of 254 nm is U_2_5_4; A method for irradiating ultraviolet rays onto a semiconductor wafer, the method comprising the step of irradiating an object to be irradiated in a second lighting state in which a mercury lamp is turned on in a state where the value of U_3_6_5/U_2_5_4 is greater than 3/2.