JP2735632B2 - Exposure pattern detection method, exposure pattern position detection method, and pattern overlay exposure method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure / drawing pattern formation in semiconductor lithography, an exposure pattern detection for evaluation, a pattern position detection, and a pattern overlay exposure method.

(Prior art)

In order to realize ultra-high integration of semiconductor integrated circuits, quantum devices, and the like, it is essential to form a fine pattern and to superimpose patterns in the order of nanometers. The pattern alignment accuracy depends on the method of detecting and measuring the alignment mark position of the exposure / drawing apparatus, the accuracy thereof, and the machine control system of the apparatus for correcting the position error.

At present, the latter is capable of controlling several tens of angstroms of position using a leaf spring control mechanism driven by electromagnetic force, an electrostrictive element, etc.On the other hand, the former has not reached the accuracy, this is the realization of high-precision alignment pattern exposure Has been hindered.

2. Description of the Related Art Conventionally, mark position detection in semiconductor lithography is exclusively based on optical technology and electron beam technology. The optical alignment mark detection method is divided into a TV image processing of an optically enlarged image of the mark on the substrate to be processed, a slit scanning method, and a method utilizing diffraction and scattered light from the mark. These capture the edge of one mark on the substrate to be processed as a bright and dark image on a CRT, detect the edge position by reflected light of a scanning light beam, or detect scattered light or diffracted light from a grid-like mark. It captures the maximum intensity position.

[Problems to be solved by the invention]

However, in the mark position detection in the conventional semiconductor lithography, the edge of one mark on the substrate to be processed is captured as a bright and dark image on a CRT, or the edge position is detected by reflected light of a scanning light beam, or Since it captures the maximum intensity position of the scattered light or diffracted light from the lattice mark, the alignment accuracy for bright and dark images has an optical resolution of only 0.3 to 0.5 μm. There was a problem that it was decided.

Even if the S / N ratio (signal / noise intensity ratio) of the optical signal is improved by electrical processing, it is difficult to improve the resolution by one digit or more.

In the double diffraction grating method using an interference waveform, a positioning error is likely to occur for an interference waveform period determined by a diffraction grating pitch. Also in the position detection technology using an electron beam, a pattern position detection error occurs due to beam fluctuation due to charge-up due to contamination of a lens barrel, thermal distortion, flicker noise of an electron gun, shot noise, and the like.

In addition, in any of the alignment techniques of the optical technique and the electron beam technique, since the mark edge position is determined from the reflection signal level instead of directly detecting the unevenness of the mark portion on the substrate, an error easily occurs. .

Further, in addition to the problems of the device itself, the cross-section of the alignment on the substrate caused in many integrated circuit manufacturing processes is a deformation of a rectangular mark, that is, a reduction in the height of the unevenness, and a loosening of the edge portion. Degrades detection accuracy. Conventional position detection using optical and electron beam techniques for determining a mark position based on a sudden change in reflected signal intensity at an uneven edge portion has a problem that a position detection error occurs.

Further, in both the conventional optical technique and the electron beam technique, it is not a hand to directly know on the spot how much the overlay accuracy of the exposure pattern itself after the alignment is achieved. The detection of the position of the overlay exposure pattern with an accuracy of the order of Angstroms cannot be determined unless it is observed by a scanning electron microscope after the development processing. Furthermore, if it was found that the pattern alignment accuracy was insufficient, the resist was stripped,
There was a problem that re-coating and re-exposure had to be performed.

As described above, with the conventional pattern position detection technology that relies on the optical technology and the electron beam technology, it is difficult to detect a pattern position with high accuracy on the order of nanometers. In addition, there is a problem that the position accuracy of the exposure or drawing pattern cannot be confirmed in-situ in the exposure apparatus or the drawing apparatus, and an alignment error is found only after the development process.

The present invention has been made to solve the above problems.

An object of the present invention is to provide a technique capable of easily detecting an exposure pattern in a pattern exposure process using at least one of light, X-rays, and particle beams as an exposure source.

Another object of the present invention is to provide a technique capable of easily detecting the value of an exposure pattern with high accuracy in a pattern exposure step using at least one of light, X-rays, and particle beams as an exposure source. It is in.

Another object of the present invention is to determine an alignment error by executing position detection with an accuracy of several tens angstroms at the time of pattern exposure in a pattern exposure step using at least one of light, X-rays, and particle beams as an exposure source. , Correct the pattern alignment error,
An object of the present invention is to provide a method for achieving high-accuracy overlay pattern exposure.

The above and other objects and novel features of the present invention are as follows.
It will become apparent from the description of the present specification and the accompanying drawings.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a method in which, during a pattern exposure step in which at least one of light, X-rays, and particle beams is used as an exposure source, a film whose film surface changes in uneven shape according to the exposure pattern is formed on a substrate. The most important feature of the present invention is that the substrate is exposed to light, and a tunnel current is passed between the coating film and the metal needle to scan the position of the metal film and detect the uneven shape from the amount of the tunnel current.

In the method for detecting an exposure pattern position, an amorphous chalcogenide film and a film made of at least one of silver and copper, or a compound film containing at least one of silver and copper may be formed on a substrate having an uneven mark. Coating the composite film over the entire substrate or at least the top of the concave and convex marks, and performing pattern exposure using at least one of light, X-rays, and particle beams as an exposure source to form a coating film over the concave and convex marks. Forming an uneven mark, detecting the uneven surface shape of the coating film in a region including the uneven mark portion on the substrate with a scanning tunneling microscope, and detecting the uneven mark position on the substrate and the exposure on the coating film. A step of comparing the pattern unevenness positions is provided.

In the pattern overlay exposure method, an exposure pattern position error determined by the exposure pattern position detection method is corrected by moving at least one of a substrate, an exposure mask, and an exposure beam position. Are exposed and drawn by superimposing them with high precision.

[Action]

According to the above-described means, a film whose film surface changes in uneven shape according to the exposure pattern is coated on the substrate and exposed, and a position is scanned by flowing a tunnel current between the coated film and the metal needle,
Since the uneven shape is detected from the tunnel current amount, the exposure pattern can be easily detected.

Further, an amorphous chalcogenide film, a film made of at least one of silver and copper,
Alternatively, a composite film with a compound film containing at least one of silver and copper is coated on the entire surface of the substrate or at least on the concave / convex mark, and at least one of light, X-rays, and particle beams is used as an exposure source. Performing pattern exposure, forming an uneven mark on the coating film above the uneven mark, detecting the uneven surface shape of the coating film in a region including the uneven mark portion on the substrate with a scanning tunneling microscope, Since the position of the upper and lower mark is compared with the position of the exposure pattern unevenness on the coating film, the position of the exposure pattern can be easily detected with high accuracy.

Further, the exposure pattern position error determined by the exposure pattern position detection method is corrected by moving at least one of the substrate, the exposure mask, and the exposure beam position, and the substrate and the exposure mask are overlapped with high accuracy. Exposure / drawing (Because the scanning tunneling microscope is used in the exposure / drawing device, the alignment error of the exposure pattern can be evaluated in Angstrom order immediately after exposure / drawing, and based on this, the position of the coated optical substrate can be moved. , The error is corrected and the main exposure is performed), so that a high-precision alignment pattern exposure / drawing can be performed.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be specifically described with reference to the drawings.

In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and their repeated description will be omitted.

Example 1 A composite film of an amorphous chalcogenide film and a silver compound film was provided on a silicon substrate whose surface was optically polished.

The composite film has a film thickness of 10 atomic% of Ge and 80 atomic% of Se.
An amorphous chalcogenide film of 00 Å (オ ン) was immersed in a cyan silver plating solution (Ag content: 32 g / 1) having a hydrogen ion concentration (pH) of 12 for 2 minutes. According to Auger analysis, the surface composition was a silver selenide compound.

Next, the surface of the composite film was exposed through a reticle having a line and space pattern of 8 μm width line and 4 μm width space using a 1/10 reduction projection exposure apparatus using light having a wavelength of 436 nm. The exposure amount at this time was ² J / cm ² . Subsequently, the surface shape of the composite film taken out of the exposure apparatus was examined with a scanning tunneling microscope.

The setting measurement mode employs a tunnel current control method, and drives a platinum probe with a piezo element under the conditions that the setting current is 1 nanoampere (nA) and the setting voltage is 1 volt (V).
The film surface was scanned. At this time, the fluctuation of the set tunnel current value showed a stability of 0.01 nA or less, and it was found that the surface of the composite film could be observed by a scanning tunneling microscope.

Further, the absence of damage on the film surface in the measurement method of Example 1 was confirmed by sufficiently reproducing the observed image even by the microscope observation many times. As a result, an uneven pattern having a cross section of the composite film shown in FIG. 1 was obtained. The exposed portion 10 has a convex shape having a width of 0.8 μm and a height of about 300 Å, and the non-exposed portion 11 sandwiched between the two convex shapes has a width of 0.4 μm. From this, it was found that the width and the position of the light exposure pattern could be easily evaluated by a scanning tunneling microscope without going through a developing step.

[Example 2] In forming the composite film of Example 1, the surface composition was changed to copper selenide by immersing in a cyan copper plating solution (pH: 12, copper content: 32 g / 1) for 2 minutes instead of the silver plating solution. A composite film as a compound was formed.

Next, when exposure and evaluation were performed under the same conditions as in Example 1, a group of 0.8 μm-wide convex shapes arranged side by side with a 0.4 μm space as in Example 1 was observed. However, in this case,
The height of the convex shape was 200 angstroms.

Example 3 The composite film shown in Example 1 was formed on a silicon substrate. Next, the substrate was loaded into an electron beam lithography apparatus, a line having a width of 0.5 μm was drawn at an acceleration voltage of 20 kV, an exposure beam current of 4 nA, and a dose of 10 ⁻³ C / cm ^2.
A line with a width of 0.5 μm was drawn again by shifting the exposure beam by the width, and this was repeated to obtain 1000 sets of line and space patterns. As a result of examining the surface shape of the discolored portion of the composite film taken out from the electron beam writing apparatus by using a scanning tunneling microscope under the same conditions as in Example 1, the convex portion was in the electron beam writing portion and the concave portion was in the non-drawing portion. A corresponding lattice pattern was obtained.

The width of the convex portion was 0.55 μm, while the width of the concave portion was 0.25 μm, indicating that the actual line width was 0.05 μm wider than the set value.

Example 4 First, the composite film shown in Example 1 was formed on a silicon substrate. Next, the substrate was loaded into an X-ray exposure apparatus, and the surface of the composite film was subjected to pattern exposure. The irradiated X-rays are soft X-rays having a wavelength range of 2 to 9 angstroms and 0.2 μm
X with gold absorber (0.97 μm thick) pattern including line and space pattern with width and 0.2 μm width
Through a line mask (gap between the composite membrane and the absorber: 2
0 μm). At this time, the exposure amount on the surface of the composite film is 112 J / cm ² . Subsequently, the surface shape of the X-ray exposed portion of the substrate taken out from the exposure apparatus was observed under a scanning tunneling microscope under the same conditions as in Example 1. As a result, 0.22
A diffraction grating having a convex shape with a width of μm and a pitch of 0.40 μm was observed.

Fifth Embodiment A fifth embodiment for performing high-accuracy pattern position detection in an exposure apparatus will be described with reference to FIGS. 2, 3, and 4. FIG.

In FIG. 2, 110 is an exposure light source, 120 is an illumination lens,
Reference numeral 130 denotes an aperture, 140 denotes a reticle, 150 denotes a projection lens, 160 denotes a stage, 200 denotes a substrate, 300 denotes a scanning tunneling microscope head, 310 and 320 denote control / drive units of the scanning tunneling microscope head 300, and an image display device. It is.

The exposure light source 110 to the stage 160 emit light (g
1/10 reduction projection exposure apparatus (light intensity: 400 mw / cm ² on the substrate) using the scanning tunneling microscope head 300 to the image display apparatus 320 to form a scanning tunneling microscope. I have.

In the fifth embodiment, the scanning / tuning microscope head 300 mounted on a micrometer head having a driving stroke of 30 mm (planar direction: x and y directions) and a positioning accuracy of 1 μm by the control / drive device 310 is moved along the optical axis. It can be freely moved up and out of the optical axis to set its position. In this case, the distance between the projection lens 150 and the substrate 200 is about 90 mm, and the size of the scanning tunneling microscope head 300 is about 25 mm in the horizontal (x direction) and about 25 m in the depth (y direction).
m, about 25 mm in height (z direction). The resolution of the scanning tunneling microscope is 20 angstroms in the plane (x and y) directions, 5 angstroms in the height (z) direction, and the maximum scanning length (x, y directions) is 30 μm.

FIG. 3A is a view showing a pattern overlay evaluation mark on the surface of the substrate to be exposed, and FIG. 3B is a view showing an exposure pattern overlay evaluation mark of the reticle.

FIG. 4 is a view showing the results of the overlay evaluation according to the present invention, and is a view showing the unevenness of the substrate surface obtained by exposing the reticle pattern shown in FIG. 3B to a mark portion on the substrate in FIG. 3A.

On the substrate 200, in addition to an integrated circuit pattern and a conventional overlay mark dedicated to an exposure apparatus to be used, an I-shape (length: 10) for overlay evaluation according to the present invention is provided near the conventional mark.
μm, width: 1 μm, depth: 400 Å) A composite film in Example 1 is coated on the entire surface of a silicon substrate 200 having a concave mark (mark 1010 in FIG. 3A) etched on the surface. The entire surface of the substrate 200 was fixed by attaching a stainless steel fitting to the surface of the composite film, and then grounded.

On the reticle 140, a metal (Cr) film is used to form a semiconductor integrated circuit pattern and a registration mark for an exposure apparatus to be used. An I-shaped mark (length: 10 μm, width: 2 μm) for position evaluation (mark 1020 in FIG. 3B) is formed.

The I-shaped mark 1020 for pattern overlay evaluation of the reticle 140 is a metal (Cr) film surface, and a region 1030 (area: 20 μm × 20 μm) including the center is formed as a punched pattern (a surface without a metal film Cr). Has become. In the design, the pattern alignment evaluation mark 1010 on the substrate 200 is located at the center of the position on the substrate 200 corresponding to the pattern alignment evaluation mark 1020 on the reticle 140.

First, the reflected light image from the reticle 140 and the substrate 200 is displayed on the CRT according to the conventional pattern superposition procedure of the exposure apparatus, and then the pattern superposition is performed. Then, light having a wavelength of 436 nm for pattern exposure (intensity: substrate Expose 5m at 400mw / cm ² ) to the area 1030 including the I-shaped mark for pattern overlay evaluation.
Seconds. Subsequently, while the reticle 140 and the substrate 200 are kept still, the scanning tunneling microscope head is inserted into the optical axis position by the control / drive unit 310, and the surface shape of the composite film near the pattern overlay evaluation mark 1010 is scanned. The image was observed with a microscope and displayed on the image display device 320. as a result,
A one-dimensional (x-direction) display surface uneven shape shown in FIG. 4 was obtained. The center concave portion is the alignment evaluation concave mark portion on the original substrate 200, the concave portions on both sides thereof correspond to the non-exposed portion of the I-shaped mark on the reticle 140, and the outer convex portion is the area 1030 of the reticle 140. In the exposure section. The distance between the center steps (the distance between 2020 and 2030) is 0.58 µm, and the distance between the right steps (the distance between 2030 and 2040) is 0.42 µm, which is asymmetric. It was found that the exposed pattern had an exposure pattern overlay error of 0.08 μm in the positive (+) direction in the x direction.

Embodiment 6 In the embodiment 5, following the evaluation of the exposure pattern overlay error, the scanning tunneling microscope head 30 was used.
0 is moved out of the optical axis by the control / drive device 310, and
The reticle is shifted by 0.08 μm in one direction by driving the stage 160 with
The pattern including the integrated circuit pattern on No. 140 was exposed according to the present invention (exposure amount: about 1.2 J / cm ² ). Subsequently, the substrate was taken out of the exposure apparatus, and the composite film was formed. In the development, the silver selenide layer on the surface is first etched with diluted aqua regia to expose the unexposed portion of the amorphous Ge-Se film, and then the unexposed portion of the amorphous Ge-Se film is exposed by a dimethylamine aqueous solution treatment. The film was etched, and the remaining silver selenide layer was removed again by a diluted aqua regia treatment. An integrated circuit pattern etched on the surface of the silicon substrate 200 and an integrated circuit pattern of a newly formed amorphous Ge—Se film were recognized with the naked eye. Next, a platinum thin layer (thickness: 200 angstroms) was attached to the entire surface of the integrated circuit pattern, and the length was measured with a scanning electron microscope. As a result, it was found that the overlay error between the two patterns was less than 200 angstroms. Was.

As can be seen from the above description, according to the first to sixth embodiments, the operation and effect as described in the section of the operation can be obtained.

As mentioned above, although the present invention was explained concretely based on an example, the present invention is not limited to the above-mentioned example.
It goes without saying that various changes can be made without departing from the scope of the invention.

〔The invention's effect〕

As described above, according to the present invention, an exposure pattern can be easily detected.

Further, the position of the exposure pattern can be easily detected with high accuracy.

In addition, high-precision alignment pattern exposure / drawing can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an uneven shape according to an exposure pattern detected in one embodiment of the present invention, and FIG. 2 is a schematic configuration of a reduction projection exposure apparatus and a scanning tunnel microscope according to one embodiment of the present invention. FIG. 3A is a view showing an overlay evaluation mark provided on the substrate, FIG. 3B is a view showing the substrate surface unevenness shape of the overlay evaluation on the reticle, and FIG. 4 is an overlay according to the present invention. It is a figure showing an alignment evaluation result. In the drawing, 10: exposure part, 11: non-exposure part, 110: exposure light source, 120: illumination lens, 130: stop, 140: reticle, 150: projection lens, 160: stage, 200 ……………………………………………………………………………………………………………………………………………………………………………………. …
… Pattern without metal (Cr) film, 2010, 2020, 2030, 2040
.... Step position.

Claims (3)

(57) [Claims] In a pattern exposure step in which at least one of light, X-rays and particle beams is used as an exposure source, a film whose surface changes in unevenness according to the exposure pattern is coated on a substrate and exposed. An exposure pattern detection method, wherein a tunnel current is caused to flow between the coating film and the metal needle to scan a position thereof, and an uneven shape is detected from the tunnel current amount. 2. A composite film of an amorphous chalcogenide film and a film made of at least one of silver and copper, or a compound film containing at least one of silver and copper, is provided on a substrate having an uneven mark. Covering the whole of the substrate or at least the top of the concave / convex mark, and performing pattern exposure using at least one of light, X-rays, and particle beams as an exposure source to form a concave / convex mark on the coating film above the concave / convex mark. Forming, detecting the uneven surface shape of the coating film in a region including the uneven mark location on the substrate with a scanning tunneling microscope, the uneven mark position on the substrate and the exposure pattern uneven position on the coating film A method for detecting an exposure pattern position, comprising a step of comparing. 3. An exposure pattern position error determined by the pattern position detection method according to claim 2 is corrected by moving at least one of a substrate, an exposure mask and an exposure beam position. A pattern overlay exposure method, which comprises exposing and drawing a mask with high accuracy.