JPS61276222A - X-ray exposure alignment - Google Patents

Abstract

PURPOSE:To easily enable the formation of the alignment mark of the X-ray mask and the alignment mark of the semiconductor substrate as well as to obtain an X-ray exposure align ment method with a superior alignment precision by a method wherein parallel X-rays of a single wavelength are respectively projected on the single crystal to be formed in the internal side of the X-ray mask and the single crystal to be formed in the semiconductor substrate, the refracted X-rays from the single crystals are made incident in the scintillator, the positions of the single crystals are detected by the scintillations from the scintillator and the positioning of the X-ray mask to the semiconductor substrate and the adjustment of the interval between the X-ray mask and the substrate are conducted. CONSTITUTION:Parallel X-rays 9; which are fine, are emitted at an interval narrowed in a dimension enough to make a first single crystal 4 bathed completely in the X-rays and have a single wavelength in wavelength; are projected on the first single crystal 4; which is formed in the internal side of the X-ray mask consisting of an X-ray transmitting film 1 and X-ray absorbers 2 and has a diameter of several nm or less; in such a way that the first single crystal 4 is completely bathed in the X-rays, refracted X-rays 11 to correspond to the specific reflection indexes (h), (k) and (l) from the first single crystal 4 are made to incide in a scintillator 134 and the position of the X-ray mask is detected by the scintillations from the scintillator 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a uX-ray exposure alignment method, and particularly to a method for aligning an X-ray mask and a semiconductor substrate.

[Conventional technology]

Conventionally, in X-ray exposure, a method using a Fresnel zone plate has been known as a method for aligning an X-ray mask and a semiconductor substrate.
al of Vacuum 5 science and T
technology) IG Volume 19, Issue 4, Page 12
24 (1981), M., Feldman et al. published the tale. In this method, a circular Fresnel zone plate mark is formed on the mask and the wafer, and a laser beam is irradiated onto this mark to match the reflection sporatra from the mask and the wafer, and between the mask and the wafer. This is an alignment method.

[Problem that the invention seeks to solve]

In the conventional X-ray exposure alignment method described above, a Fresnel Sea 70 plate mark, which is a concentric pattern, must be completely formed on the X-ray mask and the semiconductor substrate. X
Iw! To manufacture the mask, a single electron beam or a focused ion beam is used due to accuracy requirements. However, in direct writing with an electron beam or writing using a focused ion beam, it is possible to scan only 20,000 times with the beams t-X and Y perpendicular to each other. Therefore, in order to draw a circular pattern, the circle must be drawn as an approximate pattern by a collection of small rectangles. Approximating a circle to a set of small rectangles has the drawback that the amount of data required during drawing becomes enormous, which not only complicates data handling but also requires an enormous amount of time for drawing I/C. Furthermore, since the Fresnel zone plate mark becomes an approximate pattern, there is a drawback that alignment accuracy between the mask and the wafer deteriorates.

An object of the present invention is to provide a tX-ray exposure alignment method that allows alignment marks to be easily formed and has excellent alignment accuracy.

[Means for Solving the Problems] The X-ray exposure alignment method of the present invention is applicable to a first single crystal formed in an X-ray mask and having a diameter of several square meters or less, and which is thin and has the diameter of 8I! Parallel X-rays of a single wavelength are irradiated to a size that completely bathes the first single crystal, and a certain index (hkl) from the first single crystal is irradiated. The position is detected by a corresponding diffraction xit-scintillator,
Furthermore, a second single crystal having a diameter of several orders of magnitude or less formed in the semiconductor substrate is irradiated with the X-rays, and a second single crystal corresponding to a specific index (h'k't' ) from the second single crystal is irradiated with the X-ray. Diffraction
The method is constructed by detecting the position of a line using the scintillator and adjusting the positioning interval between the X-ray mask and the semiconductor substrate.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Figure wX1 is a principle diagram for explaining one embodiment of the present invention.

As shown in FIG. 1, an X-ray mask includes a silicon nitride film 1, which is a film that transmits X-rays in the exposure wavelength range, and a gold pattern 2, which is an X-ray absorber that completely absorbs t-X-rays, corresponding to the pattern to be exposed. There are also three support sections and nine structures to support them. An 8i substrate is usually fabricated as an X-ray mask. That is, after a silicon nitride film 1 and a gold pattern 2 are formed on the Si substrate, they are etched away leaving the support portion 3 on the SN substrate. When removing this St substrate by etching,
A part of the SN substrate is left by an appropriate method, and an alignment mark 4t is formed. The alignment mark 4 is selected to have an appropriate size depending on the X-ray intensity used for alignment, but is usually about 100 to 1000 microns. Further, the alignment mark 4 is arranged on the back side of the gold pattern 2 with respect to the silicon nitride film 1 so as not to become an obstacle during exposure. It is desirable that one X-ray mask has alignment marks 4 at three or more locations. Si single crystal alignment marks 6 are formed on the semiconductor substrate 5 by etching. For alignment, first, the alignment mark 4 is irradiated with a single wavelength X-ray 9 that is collimated to a size that completely covers the alignment mark 4. When a single crystal is fully irradiated with X-rays of a single wavelength, reflection occurs in a direction that satisfies Bragg's condition. In this embodiment, since a semiconductor substrate is used, the crystal orientation of the alignment mark 4 is known as is the same as that of the semiconductor substrate, and the direction in which reflection occurs is already known by calculation. Therefore, select an appropriate reflection 11t, and select a scintillator 13.
Measure from 1C. By measuring the reflections of the three alignment marks on the X-ray mask, the three-dimensional positions can be determined. Next, the wafer is also irradiated with one alignment mark 61C of X-rays 10 in the same manner as the X-ray mask, and measured using an appropriate reflection 12t-scintillator 131C. This is done for three points on seven wafers to determine the three-dimensional position. As mentioned above, the positional relationship between the X-ray mask and the wafer is measured, and the alignment accuracy is adjusted to obtain the optimum position and spacing.

Note that the alignment mark may be made of any material as long as it is a single crystal, and in the fifth embodiment, the alignment mark was formed on the back surface of the wafer, but the same effect can be obtained even if it is formed on the front surface.

〔Effect of the invention〕

As explained above, if the present invention is implemented, it will not be necessary to handle complicated and enormous amounts of data in forming alignment marks, and it will not take a huge amount of time, and there will be no deterioration in alignment accuracy due to t1 approximate alignment marks, and the process will be simple. High precision alignment can be achieved by simply forming alignment marks. Therefore, the workability of the manufacturing process is improved, and high quality semiconductors can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is an original drawing for explaining the X-ray exposure alignment method of the present invention. 1... X-ray transparent film (silicon nitride film), 2...
... X-ray absorber (gold pattern), 3 ... Support part, 4 ... Mask side alignment mark, 5
... Semiconductor substrate, 6 ... Semiconductor substrate side alignment mark, 7 ... X-ray transparent film,
...X-ray photosensitive film, 9...X@, 10...
...X-ray, 11...Diffraction X-ray, 12...
...Diffraction X1fIjA113...Scintillator-0 ¥-1 Fox procedural amendment (voluntary)

Claims (1)

[Claims] A first single crystal with a diameter of several mm or less formed in an X-ray mask is irradiated with parallel X-rays of a single wavelength narrowed to a size that completely bathes the first single crystal. is irradiated to complete the bath, and a certain index (h
A scintillator detects the position of the diffracted X-ray corresponding to
The following second single crystal is irradiated with the X-ray, and the second single crystal is
The scintillator detects the position of the diffracted X-ray corresponding to a specific index (h'k'l') from the single crystal of
An X-ray exposure alignment method characterized by aligning and adjusting the spacing between a ray mask and a semiconductor substrate.