JPS58151025A - Exposing method of photosensitive film of semiconductor wafer - Google Patents

Abstract

PURPOSE:To obtain accurate patterns, by a method wherein when a photosensitive film formed on the surface of a semiconductor wafer is adhered to a mask by vacuum extraction and exposed to light for performing photoetching, the sensitized surface is disposed to face the mask with interval determined based upon resolution, image quality and pitch error, and then they are adhered with each other by vacuum extraction. CONSTITUTION:Most defective adhesion between a photosensitive film formed on a semiconductor wafer and a mask concentrates upon the central part of the mask. This is because the adhesion can not be performed in the ideal manner as that begins at the center then spreads out to the periphery. Accordingly, when the mask is adhered to the photosensitive film by vacuum extraction, the surface and mask are disposed facing with each other with interval determined based upon resolution, image quality and pitch error, then the mask is shaped out to the convex form by vacuum extraction so that the surface and mask are first adhered at the central part then spreadingly adhered to the peripheral part. When the diameter of the wafer is 4 inches, the interval should be 30 10mum.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method of exposing a photoresist film on a semiconductor wafer, and in particular, in order to etch a semiconductor wafer, a mask is closely attached to a photoresist film deposited on the semiconductor wafer. The objective is to improve the method of

[Technical background of the invention]

Conventionally, exposure of a photoresist film on a semiconductor wafer is performed by exposing a photoresist film (1
) is deposited on the first conductor wafer (2) and the mask (3) with the K photoresist film in position is placed facing each other, and when the atmosphere is reduced in pressure, external pressure is applied to the photoresist film on one semiconductor layer as shown in Figure 2. The deformed masks are now in close contact with each other.

[Problems with background technology]

According to the background art, when a mask is brought into close contact with a semiconductor wafer, the initial atmosphere (N2) gas and the nitrogen (Nx) gas generated from the photoresist film due to exposure are filled between the contact surfaces of the two, and the close contact is partially interrupted. There was a serious problem that it was getting worse. As a countermeasure to this problem, measures have been taken such as improving the shape of the stage to maintain the orientation of the semiconductor wafer and forming grooves in the mask, but each method has the following drawbacks. First of all, the former has difficulty in controlling the stage shape and variations due to stage manufacturing, while the latter has difficulty in cutting grooves, increases reproducibility, increases cost, and increases defect, resulting in poor A-turning.

[Purpose of the invention]

The present invention provides an exposure method for a photoresist film of a semiconductor phenol 1 which overcomes the above-mentioned defects.

[Invention 0III] This invention involves attaching a mask to the photoresist film of a semiconductor phenol in advance at intervals determined based on resolution, image quality, and pitch deviation, and then exposing the mask to light by bringing the mask close together under reduced pressure. Photosensitive IIO characterized by etching
This is an exposure method.

[Embodiments of the invention]

Next, the invention will be described in detail with reference to one embodiment. Most of the poor contact between the photoresist film of the semiconductor wafer and the mask occurs in the center of the mask. This is because the mask, wafer, and 0*m do not necessarily start from the center and sequentially reach the edges.
This is because it does not become "IT". The results of an attempt to further analyze this close exit are described below.

First, the mask placed above the wafer is depressurized at the bottom and becomes convex downward, starting to come into close contact with the wafer. The photoresist coating surface (top surface) can be either convex or concave. Therefore, considering the difference in the shape of the wafer in the first stage, we set the starting point between the mask and the wafer at the center,
Considering the distance between the mask and the wafer, the distance between the mask and the wafer is 5 inches for the 4-inch diameter square in the example (mask 0 BLJ when the Qq star is closely spaced and 0 m 1 l K')! Perform the third measurement.
The results shown in Figure 9 were obtained. Distance between mask and wafer (1)
was set in five stages: o, 10, 20, 30, 40 (μ steel), and the amount of warp of the mask was 20p or more, as shown by the × mark in the figure for close contact and the circle mark in the figure for exposure. It became clear that it entered the region of downward convexity.

Next, the relationship between mask-wafer spacing and resolution was investigated, and the results shown in FIG. 4 were obtained. This 4μ purchase pattern of the solution degree Hiroshizu! : 3 All, exposed for J turn #L
After I inspected the pattern for omissions, the yield ratio of round and thin 3 μm patterns was important, and the mask-to-wafer spacing was 20 seconds or more, and the yield was noticeably better.

Next, the relationship between the mask-wafer spacing and the image quality (grain) is shown in Figure 5. , Mu grade has a very clear square shape, B grade is 1i & which is almost similar to this, and is considered to be a good product, C grade has a rectangular corner and is unsuitable for use, and D grade has only unresolved. This result shows that the mask-wafer spacing is 1
A voice above 0 is good for Arashi.

Next, I will explain the issue of pitch deviation. While FIG. 6 shows a normal pattern with no pitch deviation, FIG. 7 shows a pattern with a pitch deviation.

As shown in Figure 10, the horizontal axis represents the amount of pitch deviation, and the vertical axis represents the number of occurrences (f
The results are summarized in the table below.

(1 Su, 1・Margin) As seen in the table, 1. The amount of pitch deviation is determined by the setting interval.
There is a tendency for it to increase over time.

OWIFis degree, grade, pitch deviation 034! To summarize the matters, (1) Method 1 of bringing the mask into close contact with the wafer: Place the two in advance with the following distance apart, and reduce the pressure to make six masks, and bring the mask into close contact with the wafer from the center to the periphery one by one. , Q+) Furthermore, the above mentioned pre-separation interval is set to 3o±10μ- for a 4-inch diameter semiconductor wafer based on the resolution, grade, and zero pitch deviation requirements (the mask is 15±smo convex with respect to the wafer). how to.

becomes.

In addition, wafer! The spacing between the masks is determined by the wafer diameter and the mask diameter (
The mask diameter is appropriately adjusted by K (generally determined by tK).

〔Effect of the invention〕

According to the method of the present invention, a round mask/(turn) for etching a semiconductor wafer can be developed on the photoresist film of the wafer with high precision, which is extremely effective in increasing the density of semiconductor devices.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of a round exposure head section to explain the background art, and FIG. 3 shows the relationship between the mask-wafer spacing and the mask rectification amount! 1 and 4 are diagrams showing the relationship between the mask-wafer spacing and the grade, and FIG. 5 is a diagram showing the relationship between the mask-wafer spacing and the solution g1 degree.
Figures 6 to 10 show pitch deviations, ms diagrams and Figure 7 are regular box diagrams of rounded patterns to explain pitch deviations, and Figures 8, 9, and 10 show mask-wafer spacing, respectively. FIG. 4 is a diagram showing the distribution of pitch deviation when is 20, 30, and 40 μm. 1 Photoresist film of semiconductor wafer 2 Semiconductor wafer 3 Mask agent Patent attorney Inoue - Male Figure 3 (λm) Square 7 and wafer simultaneous movement - Figure 4 % Figure 6 Figure 7 Figure 8 Pin needle 6 Figure 1O

Claims (1)

[Claims] (11) A photoresist film is coated on the main surface of the semiconductor substrate 1, and a mask is brought into close contact with the photoresist film under reduced pressure to expose the semiconductor substrate 1. A photosensitive method for semiconductor wafers characterized by placing a photosensitive film on a semiconductor wafer and a mask at a distance determined based on the resolution, film quality, and pitch deviation K, and then applying a reduced pressure to bring the mask into close contact with each other for exposure. mow light method. (2) When the diameter of the semiconductor wafer is 4 inches, the distance between the photoresist and the mask is 30±I Q Jlllli
The method for exposing a photoresist film of a semiconductor wafer according to claim 1, wherein the photoresist film is exposed in a semiconductor wafer.