JP2855868B2 - Laser trimming alignment mark, semiconductor device, and method of manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment mark for laser trimming used in a semiconductor device manufacturing process.
When a semiconductor device having the alignment mark, and to a method of manufacturing a semiconductor device.

2. Description of the Related Art In general, alignment of a wafer and a mask pattern at the time of reduced projection exposure in a semiconductor device manufacturing process, alignment of cutting a laser fuse on an element pattern by using a laser trimming device, and the like are performed with high accuracy. Required.

[0003]

2. Description of the Related Art For example, when a laser fuse on an element pattern is cut using a laser trimming device, it is necessary to align the wafer on the trimming device.
Further, the coordinate system of the element pattern fluctuates due to expansion and contraction of the element pattern in the manufacturing stage, and may not coincide with the coordinate system of the laser trimming device. If the coordinate system of the design data of the element pattern on the wafer and the coordinate system of the laser trimming device do not match, the coordinates of the fuse cutting position obtained from the design data will fluctuate, so that the laser beam will be irradiated to the correct position. And it may cause a laser fuse cutting failure.

Therefore, in order to accurately match the coordinate system of the laser trimming device with the coordinate system of the element pattern, alignment marks are formed at several places in each element pattern. The conventional alignment mark is formed of an Al layer having a high reflectance, and usually has an L-shaped or I-shaped convex planar shape. The background around each alignment mark is a field area without any other opaque layers.

[0005] The laser beam is irradiated in the X direction or Y direction of the element pattern.
The position of the alignment mark is detected from the change in the vertical reflected light intensity between the alignment mark and the surrounding background. After correcting the positioning of the element pattern in the X, Y, and θ directions from the coordinates of the alignment mark, and matching the coordinate system of the laser trimming device with the coordinate system of the element pattern, the coordinates of the accurate cutting position of the laser fuse are calculated. decide.

[0006]

Usually, a cover film such as PSG or a plasma nitride film is formed on the Al layer of the alignment mark or on the field region. If a cover film is formed on the Al layer or the field oxide film,
Vertical reflection of laser light also occurs on the cover film. Then
Laser light, which is coherent light, interferes with the vertical reflection on the Al layer, the vertical reflection on the cover film, the vertical reflection on the field oxide film, and the vertical reflection on the cover film. Therefore, the vertical reflectance on the Al layer and the vertical reflectance on the field oxide film depend on the thickness of the cover film that reflects the laser light vertically. Depending on the thickness of the cover film, the vertical reflectance on the Al layer and the vertical reflectance on the field oxide film become almost the same, and the contrast between the alignment mark and the background surrounding the mark deteriorates, making it impossible to align. In some cases,

For this reason, a method of removing the cover film on the Al layer by etching is also used, but in that case, there is a restriction that an alignment mark cannot be arranged at an arbitrary position in the element pattern.

According to the present invention, when performing laser trimming,
At different vertical reflected light intensity de target pattern definitive alignment mark and the back <br/> click ground (background)
Therefore , regardless of the thickness of the cover film, the contrast difference is increased, the S / N ratio is improved, and the laser can be accurately aligned.
Alignment mark for trimming, the alignment mark
It is an object of the present invention to provide a semiconductor device having the above, and a method for manufacturing the semiconductor device.

[0009]

The above object is achieved by the following constitutions.
Alignment marker for laser trimming according to the present invention comprising:
Click, semiconductor device, and thus is achieved a method of manufacturing a semiconductor device. Alignment marker for laser trimming of the present invention
The high reflection area for vertically reflecting the position detection light and the high reflection area
The position detection light is disposed adjacent to the reflection area and scatters the position detection light.
Laser with a low reflection region to reduce vertical reflection
In the trimming alignment mark, the high reflection area
And larger than the spot diameter of the position detection light.
A first light reflecting film having a flat surface of
Area having a width smaller than the spot diameter.
A number of second light reflecting films, and covering the first and second light reflecting films.
A flat surface on the first light reflecting film,
The second light reflecting film has a plurality of second light reflecting films on the second light reflecting film.
And a transparent cover film that becomes a corresponding uneven surface.
Features.

[0010] The plurality of second light-reflective films may be positioned by the position detection.
Stripes extending in the direction perpendicular to the scanning direction of emitted light
Or a dot pattern or checkerboard pattern
It can be formed into turns. Furthermore, strike
Stripe on top of the step-forming film
The reflective film is formed at an angle, or
At the center of the formed film for forming steps
Can also be formed by contacting a reflective film with
It is.

According to the semiconductor device of the present invention, the position detection light is vertically
A high-reflection area to be reflected, and disposed adjacent to the high-reflection area
Scatter the position detection light to reduce vertical reflection
A high reflection area and a low reflection area.
One of the areas is the target pattern and the other is the background
With alignment marks for laser trimming
In the semiconductor device, the alignment mark may
And is larger than the spot diameter of the position detection light.
A first light reflecting film having a flat surface of a suitable size;
It is located in the reflection area and has a width smaller than the spot diameter.
A plurality of second light reflecting films, and the first and second light reflecting films
Covering the film, forming a flat surface on the first light reflecting film,
The recesses of the plurality of second light reflecting films are formed on the plurality of second light reflecting films.
A transparent cover film that becomes an uneven surface corresponding to the convexity
It is characterized by the following.

According to the method of manufacturing a semiconductor device of the present invention,
Forming a fuse portion on the substrate;
Step of forming a light-reflecting film with high reflectivity in a region other than the portion
And patterning the light reflecting film to allow the position detecting light
The first light source having a flat surface of a size larger than the
And a plurality of films having a width smaller than the spot diameter.
Forming a second light reflecting film; and forming the first light reflecting film.
The first light on the film and on the plurality of second light reflecting films;
A flat surface is formed on the reflection film, and the flat surface is formed on the plurality of second light reflection films.
With this, an uneven surface corresponding to the unevenness of the plurality of second light reflecting films is formed.
By forming a transparent cover film, the first light
The position detection light is vertically reflected in the area where the reflective film is present.
A high reflection area, where the plurality of second light reflection films are present.
Scatter the position detection light to reduce vertical reflection.
Making a low reflection area, and the high reflection area and the
The position detection light is irradiated almost vertically to the low reflection area,
Calculate the position of the fuse on the device coordinates from the reflected light intensity.
And cutting the fuse by irradiating the fuse with laser light.
And

[0013]

The alignment mark for laser trimming of the present invention
And a high reflection area and a low reflection area in the alignment mark .
Is a unique configuration as described above,
One of the reflection area and the low reflection area as the target pattern
By using the other as background
It is possible to make the vertical reflected light intensity greatly different.
As a result, regardless of the thickness of the cover film, the reflectance
Trust difference can be significantly increased.
You .

[0014] In the method of manufacturing the semi-conductor device of the present invention enables a large contrast differences, as described above
Fuse on the semiconductor substrate using the alignment mark
Position (ie, trimming position) is calculated with high accuracy,
This position is irradiated with laser light to cut the fuse.
Can be Therefore, a trimming defect and a semiconductor device manufacturing defect do not occur.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an alignment mark according to the present invention will be described with reference to FIG. FIG. 2A is a plan view of the alignment mark 1 according to the present embodiment, and FIG. 2B is a cross-sectional view of the alignment mark 1 along AA of the present embodiment.

A field oxide film 10 is formed on a semiconductor substrate 12.
Is formed, and the PSG layer 8 is formed on the field oxide film 10. The position detection target 2 and the vertical reflectance reduction region 3 are formed on the PSG layer 8. The width of the position detection target 2 in the laser light scanning direction is about twice the spot diameter of the laser light. The vertical reflectance reduction region 3 is formed of Al extending in a direction perpendicular to the laser beam scanning direction.
The layer 4 has a stripe structure. The width of the Al layer 4 having the stripe structure is 1/3 or less or 2 μm or less of the laser spot diameter, and the width of the gap between the Al layers 4 is 1/2 or less or 3 μm or less of the laser spot diameter.

A cover film 6 such as a PSG or a plasma nitride film is formed on the position detection target 2 and the vertical reflectance reduction region 3. Al with stripe structure
Due to the layer 4, the cover film 6 in the vertical reflectance reduction region 3 has an uneven shape. In relation to the thickness of the cover film 6 and the width of the gap between the Al layers 4, the cover film thickness is one of the gap width.
The best is about / 2 times, but may be about the same.

In this embodiment, the laser light source for position detection is
An infrared laser (not shown) having a wavelength of 1030 to 1060 nm and a spot diameter of 6 μmφ is used. Therefore, in this embodiment, the width 12 of the position detection target 2 in the laser beam scanning direction is
μm, the width of the Al layer 4 having a stripe structure is 1 μm which is 1/6 of the laser spot diameter, the width of the gap between the Al layers 4 is 1.4 μm which is about 1/4 of the laser spot diameter, and the cover film thickness is 1 μm of the gap width. /0.7 μm.

Next, the operation will be described. When the scanned laser beam for position detection reaches the vertical reflectance reduction region 3, the laser beam is reflected by the cover film 6 and the Al layer 4 having a stripe structure. The surface of the cover film 6 in the vertical reflectance reduction region 3 is
The Al layer 4 having a stripe structure has an uneven shape. Therefore, the uneven surface of the cover film 6 and the Al layer 4
The laser light is scattered at the edge portion of, and the vertically reflected portion is significantly reduced. In addition, since the Al layer 4 is a stripe that is sufficiently narrower than the spot diameter of the laser beam, the ratio of scattering at the edge portion is larger than that at the flat portion of the Al layer 4.
Vertical reflectance decreases.

When the laser beam reaches the target 2 for position detection, the surface of the target 2 for position detection has a large area with respect to the laser beam diameter and is perpendicular to the laser beam, so that the vertical reflectance is high. Cover film 6 of target 2 for position detection
Although the vertical reflectance varies depending on the thickness of the cover film 6 due to the reflection on the surface, the vertical reflected light of the position detection target 2 is reflected vertically in the vertical reflectance reduced area 3. It becomes very large depending on the strength. In this manner, the difference between the vertical reflectance of the position detection target 2 and the vertical reflectance of the vertical reflectance reduction region 3 becomes large, so that a reflectance waveform with good contrast can be always obtained.

The present embodiment is also characterized in that an Al layer 4 having a high reflectivity is used for forming the cover film 6 having irregularities (steps). By forming it on the same layer as Al of the position detection target 2, the Al of the vertical reflectance reduction region 3 is simultaneously formed in the manufacturing process of the position detection target 2.
Since the layer 4 can be formed, an error factor in the manufacturing process can be eliminated.

Further, since the Al layer can be formed thicker than other materials, the curvature of the unevenness of the cover film 6 can be increased. 0.5 μm for polycrystalline silicon, etc.
It can be formed only to a thickness of about m, but can be formed to a thickness of about 1 μm when Al is used. Therefore, the effect of scattering the laser light on the surface of the cover film 6 is increased. Therefore,
There is no problem even if Al having high reflectivity is used, and it is rather convenient.

A second embodiment of the alignment mark according to the present invention will be described with reference to FIG. FIG. 2A is a plan view of the alignment mark 11 according to the embodiment, and FIG. 2B is a cross-sectional view of the alignment mark 11 according to the embodiment along BB.

In this embodiment, the vertical reflectance reduction region 3 is made of aluminum.
It is characterized in that the layer 4 is formed in a dot shape. By making the Al layer 4 into a dot shape, the area of the flat portion of the Al layer 4 is reduced, the edge portion is increased, and the unevenness of the upper cover film 6 is further reduced as compared with the striped Al layer 4 of the first embodiment. Can be more. Therefore, a more excellent vertical reflectance reduction effect than the stripe-shaped Al layer 4 of the first embodiment occurs.

The conditions for the width of the Al layer 4 having a dot structure to be 1/3 or less or 2 μm or less of the laser spot diameter and the width of the gap between the Al layers 4 to be 1/2 or less or 3 μm or less of the laser spot diameter are as follows. This is the same as the first embodiment.

A third embodiment of the alignment mark according to the present invention will be described with reference to FIG. The alignment mark 21 according to the present embodiment is characterized in that the Al layer 4 in the vertical reflectance reduction region 3 is formed in a checkered shape. By forming them in a checkered shape, a vertical reflectance reduction effect similar to that of the second embodiment can be obtained.

In FIG. 3, the checkered black portion is Al.
In the layer 4, the white portion is a gap portion. A fourth embodiment of the alignment mark of the present invention will be described with reference to FIG. 2A is a plan view of the alignment mark 22 according to the present embodiment, and FIG. 2B is a plan view of the alignment mark 2 according to the present embodiment.
FIG. 2 is a sectional view taken along line CC of FIG.

An Al layer 14 for forming a step is formed on the PSG layer 8.
Is formed, the target 2 for position detection is formed via the PSG layer 16, and Al is formed in the same layer as the target 2 for position detection.
A of a stripe structure is formed on the layer 14 via the PSG layer 16.
An l layer 4 is formed. The Al layer 14 becomes a step, and P
The Al layer 4 on the SG layer 16 is inclined.

A cover film 6 is formed on the position detection target 2 and the Al layer 4. The cover film 6 in the vertical reflectance reduction region 3 has an inclined surface due to the Al layer 4 inclined in a stripe structure, and has a concave shape due to a gap between the Al layers 4.

The present embodiment is characterized in that in the Al layer 4 and the cover film 6 thereover, the vertical reflectance is reduced by reducing the horizontal plane as much as possible. A fifth embodiment of the alignment mark of the present invention will be described with reference to FIG. Same figure
(a) is a plan view of the alignment mark 23 according to the present embodiment,
FIG. 3B shows the D-position of the alignment mark 23 according to the present embodiment.
It is D sectional drawing.

An Al layer 14 for forming a step is formed on the PSG layer 8.
Is formed, and a contact hole is formed in the PSG layer 16 above the Al layer 14. The position detection target 2 is formed via the PSG layer 16, and the Al layer 4 is in contact with the position detection target 2 above the Al layer 14 via the contact hole of the PSG layer 16 in the same layer as the position detection target 2. Al
The layer 4 has a recess at the center for the contact hole. Due to the gap between the concave portion at the center of the Al layer 14, the edge at the peripheral portion, and the Al layer 4, the cover film 6 in the vertical reflectance reduction region 3 forms an uneven portion.

This embodiment is characterized in that, as in the fourth embodiment, in the Al layer 4 and the cover film 6 thereon, the vertical reflectance is reduced by reducing the horizontal plane as much as possible. The Al layer 4 can obtain a certain effect even if the material is formed of polysilicon, PSG or the like instead of Al.

FIG. 6 shows an example of the shape of the target 2 for detecting the position of the alignment mark according to the present invention. 3A to 3D, the Al layer in the vertical reflectance reduction area 3 is formed in a dot shape, and corresponds to the second embodiment of the alignment mark of the present invention. 14A shows an L-shaped target pattern, FIG. 14B shows an I-shaped target pattern, FIG. 14C shows a II-shaped target pattern, and FIG. 14D shows a + -shaped target pattern.

FIG. 7 shows reflectance measurement data using the alignment mark of the present invention. In the figure, (a), (b), (c)
Are the reflectance curves of the alignment mark on which the scattering pattern of the present invention is formed, and (a '), (b'), (c ') are the reflectance curves of the conventional alignment mark without the scattering pattern. It is. (A) and (a ') have a standard thickness of the cover film, (b) and (b') have a thickness of -0.1 μm with respect to the standard, and (c) and (c ') have a standard thickness. It is +0.1 μm with respect to the standard.

As is clear from FIGS. 4A, 4B and 4C, the alignment mark on which the scattering pattern of the present invention is formed has a reflectivity which is not affected by the cover film thickness and the cover film has a reflectivity. Regardless of whether the thickness is smaller or larger than the standard, the contrast difference between the target pattern region and the scattering pattern region is large.

On the other hand, in the figures (a '), (b'), (c ')
As is clear from the above, in the conventional alignment mark having no scattering pattern, the reflectance changes even if the cover film thickness is smaller or larger than the standard, and the contrast difference between the target pattern region and the field region is small. .

A sixth embodiment of the alignment mark according to the present invention will be described with reference to FIG. FIG. 7A is a plan view of the alignment mark 24 according to the present embodiment, and FIG. 7B is a cross-sectional view of the alignment mark 24 according to the present embodiment taken along line E-E.

The PSG layer 8 is formed on the field oxide film 10. The position detection target 2 and the vertical reflection area 18 are formed on the PSG layer 8. The position detection target 2 is formed in a stripe structure of an Al layer 20 extending in a direction perpendicular to the laser light scanning direction.
The width of the vertical reflection region 18 in the laser light scanning direction is about twice the spot diameter of the laser light. A PSG cover film 6 is formed on the position detection target 2 and the vertical reflection area 18.
Are formed. The cover film 6 of the target 2 for position detection has an uneven shape due to the Al layer 20 having a stripe structure.

Next, the operation will be described. When the scanned laser beam reaches the vertical reflection area 18, the vertical reflection area 18 has a large area with respect to the laser beam diameter and is horizontal, so that the vertical reflectance is high.

When the laser beam for position detection reaches the target 2 for position detection, the laser beam is reflected by the cover film 6 and the Al layer 20 having a stripe structure. The surface of the cover film 6 of the target 2 for position detection is an Al layer 2 having a stripe structure.
0 indicates an uneven shape. Therefore, the laser light is scattered on the uneven surface of the cover film 6 and the edge portion of the Al layer 20, and the vertically reflected component is significantly reduced. In addition, since the Al layer 20 is a stripe that is sufficiently thinner than the spot diameter of the laser beam, the ratio of scattering at the edge portion is higher than that at the flat portion of the Al layer 20, and the vertical reflectance is reduced. The vertical reflected light from the position detection target 2 is significantly weaker than the light intensity that is vertically reflected in the vertical reflective area 18. Therefore, the difference between the vertical reflectance of the position detection target 2 and the vertical reflectance of the vertical reflection area 18 becomes large, so that a reflectance waveform with good contrast can always be obtained.

The alignment mark 24 of this embodiment scatters position detection light by a position detection target having an uneven portion to reduce vertical reflection, and vertically reflects the position detection light in a vertical reflection region having a convex flat portion. It is characterized by: That is, the roles of the convex flat portion and the concave / convex portion are opposite to those of the first embodiment. Therefore, the uneven portion of the position detection target for reducing the vertical reflection, in addition to the stripe shape,
The dots and checkered shapes used in the second to fifth embodiments may be formed.

As described above, according to the present embodiment, a reflection waveform of an alignment pattern having a high contrast can be obtained irrespective of the variation of the cover film thickness between lots, thereby improving the alignment accuracy of a laser trimmer or the like. Can be In addition, since the multiple reflection is caused due to the difference in the thickness of the cover film and the contrast is deteriorated, the cover film on the Al alignment pattern is etched, but this step is not required. Further, the portion of the position detection target 2 which is the vertical reflectance reduction area can be formed in an L-shaped pattern, an I-shaped pattern, a II-shaped pattern, a + -shaped pattern, or the like.

The alignment mark of the present invention is not limited to the above embodiment, but can be variously modified. For example, the material for pattern formation of the vertical reflectance reduction region 3 may be other than Al, as long as the scattering effect can be increased.

Further, the dot shape in the second embodiment may be another shape, for example, a square or a circle or a rectangle close thereto. Next, the laser trimming technique using the alignment mark according to the present invention will be described by taking as an example a case where a fuse of a redundant bit of an IC chip is cut.

FIG. 9 illustrates a very simple circuit of the redundancy bit 26. As shown in FIG.
A fuse 27 and a resistor 28 are connected in series between the points, and an intermediate b
Branching from a point, the inverter 29 is connected. Fuse 2
Assuming that the resistance value of the resistor 7 is R, the resistance value of the resistor 28 is 2R, and the voltage at the point a is Vcc, the potential at the point b is 2/3 Vcc before the fuse 27 is cut and 0 after the fuse 27 is cut. This can be made to correspond to “1” and “0”, and the cutting of the fuse 27 can be used in the process of forming the address storage ROM.

FIG. 10 is a very schematic cross-sectional view of the semiconductor device in which the alignment mark and the redundancy bit are formed, which is cut at the fuse portion of the redundancy bit. A field oxide film 10 is formed on a semiconductor substrate 12, and then a PSG layer 8 is formed on the field oxide film 10. Then, a fuse 27 using polysilicon or the like for the redundant bit 26 is provided on the PSG layer 8, and the PSG layer 8 '
Are laminated. Next, P outside the region for forming the redundancy bit 26 is set.
On the SG layer 8 ', the first alignment mark of the present invention is provided.
The position detection target 2 formed on the flat portion of the Al layer 4 and the vertical reflectance reduction region 3 formed by the stripe structure of the Al layer 4 are formed exactly as in the embodiment of FIG. A cover film 6 such as a nitride film is formed.

FIG. 11 shows an example in which the alignment mark 31 is arranged in the IC chip 30 on which the redundant bit 26 is formed. FIG. 3 schematically illustrates a fuse 27 portion of the redundant bit 26. In this example, the target pattern of the position detection target 2 of the alignment mark 31 is an I-shaped pattern, and the X-axis target 32a and the Y-axis target 32
Four pairs of b are provided.

FIG. 13 is a block diagram of an example of a laser trimming device 34 used for the laser trimming technique using the alignment mark according to the present invention, which will be described below with reference to FIG. Light source 35 for excitation such as krypton arc lamp
a, Coherent parallel light is emitted from a laser light source 36 including a laser rod 35b as an active medium such as an Hd: YAG crystal and a reflecting mirror 35c forming a resonator. The Q switch 37 is connected to the fuse 27 of the redundant bit 26.
Is turned on, a single pulse (giant pulse) having a narrow time width and a large peak output is oscillated. The attenuator 38 attenuates the intensity of the laser beam as needed (for example, at the time of positioning), and a beam expander 39.
Converts a thin parallel light beam into a thick parallel light beam.

The first half mirror 40 is provided with the laser light source 3
A part of the laser light incident from 6 through the Q switch 37, the attenuator 38, and the beam expander 39 is partially transmitted and made incident on the incident light power meter 41, and the reflected light is directed to the objective lens 42 which performs focus control. .

The incident light whose focus has been controlled is
IC chip 30 on which redundancy bit 26 and alignment mark 31 placed on XY stage 43 are arranged
Is irradiated on the wafer 44 on which is formed. The Q switch 37, the attenuator 38, the beam expander 39, the first half mirror 40, and the objective lens 42 constitute a laser beam irradiation unit 36 '.

The second half mirror 45 reflects a part of the reflected light from the wafer 44 returning from the incident optical path and passing through the objective lens 42 to be incident on the monitor TV camera 46, and transmits the transmitted light to the reflected light power. The light enters the meter 47. The monitor TV camera 46 grasps the situation on the wafer 44 at the time of trimming including alignment.

The incident light power meter 41 and the reflected light power meter 47 detect the intensity of the incident light and the intensity of the vertically reflected light, respectively.
The detected intensity is output to the reflectance calculating circuit 48. The reflectance calculating circuit 48 calculates the vertical reflected light intensity / incident light intensity = reflectance, and outputs the reflectance data to the arithmetic processing means 49 for controlling the entire apparatus.

Storage means 5 connected to arithmetic processing means 49
The first storage unit 50a of 0 stores primary test data such as a redundancy chip and address data, and the second storage unit 50b stores coordinates of a target for position detection of an alignment mark and fuse coordinates of a redundancy bit 26. And the like, and the ROM 50c stores the arithmetic processing means 4
9 stores a system program for performing various controls on the apparatus.

The arithmetic processing means 49 includes a reflectance calculating circuit 48
The coordinates of the center of the X-axis target 32a and the center of the Y-axis target 32b are obtained as coordinates on the apparatus from the reflectance calculated in
Various data stored in the storage means 50 are appropriately read, and the coordinates on the device of the alignment mark 31 determined from the reflectance are compared with the coordinates on the device in advance and the coordinates on the device are calculated from the comparison. A conversion coefficient with respect to the coordinates is obtained by design, and the conversion coefficient and the redundancy bit 26 stored in advance are calculated.
The position of the fuse 27 to be cut is determined by coordinates on the apparatus from the coordinates of the fuse 27 to be cut in design coordinates, and the fuse 27 is cut by irradiating a laser beam based on these data, and the entire apparatus is controlled overall. .

RAM 5 provided in storage means 50
0d temporarily stores data such as the conversion coefficient calculated by the arithmetic processing circuit 49 and the position of the fuse to be cut at the coordinates on the device, and responds to reading from the arithmetic processing circuit 49 as necessary.

The stage driving means 51 includes the arithmetic processing means 4
The XY stage 43 is moved in the X and Y directions according to the instruction of 9, and the position of the fuse 27 at which the redundant bit 26 of the wafer 44 mounted on the stage is cut coincides with the laser beam irradiation position of the optical system.

The light source driving means 52 turns on and off the Q switch 37 and the attenuator 38 in accordance with the instruction of the arithmetic processing means 49 at the time of emitting a laser pulse or at the time of positioning.
Then, the light intensity of the laser light is adjusted.

Hereinafter, referring to the processing procedure shown in FIG.
The operation of the laser trimming device 34 will be described. First, the alignment is performed. The alignment is performed by detecting the point of the alignment mark 31 arranged on the chip 30 formed on the wafer 44 by the coordinates on the apparatus.
Here, as shown in an example in FIG.
Center of axis target 32a and Y axis target 32b
Of the line extending from the center of the target 2 for position detection. If the alignment marks 31 are provided at the four corners of the chip 30, there will be four points. In addition, it is sufficient to detect at least two, and if more than two are detected, the accuracy of positioning is increased. The detection of each point is performed by detecting each X-axis target and each Y-axis target.

Step (hereinafter, referred to as ST) 1 is the detection of the first point, which includes detection of an X-axis target in step ST1x and detection of a Y-axis target in step ST1y.

FIG. 15 shows a processing procedure for detecting the X-axis target in step ST1x. In step ST1 _x1 , the reflectance calculation circuit 48 measures the reflectance and obtains the center of the target by coordinates on the apparatus. That is, the stage driving means 51 is operated to move the XY stage 43 in the X direction, and the light source driving means 52 is operated to scan the laser beam linearly in a range of ± 20 to 80 μm before and after the expected position of the target. The upper portion is irradiated with a laser beam, and during scanning of the section once, about 1024 pieces of digital information of the reflectance determined by the ratio of the vertical reflected light intensity / incident light intensity are captured. At this time, the target width of the coordinates on the apparatus is determined from the difference between the scattering pattern of the alignment mark 31 and the reflectance of the target pattern. The target width obtained by the coordinates on the apparatus does not exactly match the target width due to the design due to the scattering of the edge of the position detection target 2 of the alignment mark 30. If the target width obtained by measuring the reflectance is substantially equal to the target width in design, the coordinates of the center of the target are obtained as coordinates on the apparatus.

In step ST1 _x2 , the stage driving means 51 is operated to move the XY stage 43 by about 5 to 7 μm in the Y direction.
Step ST1 _x1 at a position different from the pre-scanning position
Then, the coordinates of the center of the target are obtained as coordinates on the apparatus.

In step ST1 _x3 , the difference between the coordinates of the centers of the two targets determined above is determined, and it is determined whether or not the difference is within a set error (for example, 0.3 μm). If the difference is not within the error,
The above steps are repeated by moving the XY stage 43 in the Y direction by about 5 to 7 μm. If it is within the set error, the process proceeds to the next step ST1 _X4 .

In step ST1 _X4 , of the coordinates of the center position of the target obtained in the above step, the average of the coordinates of the two measurement positions where the error is minimized is calculated, and the calculated value is used as the measurement point of the X-axis target 32a. X of the coordinates on the device
Coordinates.

Steps ST1 _{X1 to} ST1
By the step of _X4 , the X coordinate of the first point in the on-device coordinates is obtained. Step S for detecting the Y-axis target
At T1y, the same operation is performed as in the step ST1x for detecting the X-axis target 32a, except that the X-axis and the Y-axis are interchanged, and the Y-coordinate of the Y-axis target 32b in the on-device coordinates is detected. , At step ST1, the X.D. The Y coordinate is obtained.

The operations performed in step ST2, step ST3, and step ST4 are substantially the same as those in step ST1, and a description thereof will be omitted. At least step ST1
And step ST2 or, if necessary, step ST2.
3. By adding the operations of step ST4, the X and Y coordinates of the first point and the second point of the chip 30 in the wafer 44 mounted on the XY stage 43 in the coordinates on the apparatus.
The coordinates are obtained, and the third point, the fourth point,
The X and Y coordinates of the point on the device coordinates are obtained.

Next, in step ST5, a conversion coefficient between the coordinates on the apparatus and the coordinates on the design is calculated. This is done by comparing the coordinates of each point in the on-device coordinates obtained from at least two of the above-described steps ST1 and ST2 with the coordinates of each point in the previously stored design coordinates. Done. For example, the distance and the direction between the coordinates of the first point and the second point in the coordinates on the device, the distance and the direction between the coordinates of the first point and the second point in the previously stored design coordinates, and By comparison, the degree of expansion and contraction and expansion of the element pattern of the semiconductor device at the manufacturing stage can be grasped, and the conversion coefficient between the on-device coordinates and the design coordinates can be calculated.

Next, in step ST6, cutting is performed from the redundant chip and address data of the primary test previously stored in the first storage section 50a and the design fuse coordinate data previously stored in the second storage section 50b. The coordinates in the design coordinates of the fuse 27 to be read are read out.

Next, in step ST7, step ST
A conversion coefficient between the on-device coordinates and the design coordinates calculated in 5;
The position of the fuse 27 to be cut is determined by the coordinates on the device from the coordinates of the fuse 27 to be cut which are read in step ST6 in design coordinates. Then, the obtained data is temporarily stored in a file of the RAM 50d in step ST8.

Next, according to the data filed in step ST8, the XY stage 43 is controlled by the stage driving means 51 in step ST9, and the wafer 44 is controlled.
The irradiation position of the laser light is adjusted to the position of the fuse 27 to be cut in the upper redundant chip 26, and a laser pulse is emitted.
Then, XY stage control and laser pulse emission are repeated according to the file.

As described above , in the above example , the reflectivity of the laser beam reflected by the alignment mark is measured, and at least two coordinates of the position of the alignment mark are expressed in coordinates on the apparatus from the change in the reflectivity. The conversion coefficient between the on-device coordinates and the design coordinates is calculated by comparing the on-device coordinates obtained by the reflectance measurement of the point with the coordinates of the pre-stored design coordinates. From the redundant chip of the primary test stored in advance, the address data, and the coordinate data at the design coordinates of the design fuse,
The position of the fuse to be cut is determined with high precision in the coordinates on the apparatus, and laser light is emitted accurately. For this reason, fuse cutting failure of the redundancy bit does not occur.

In the above embodiment, the alignment mark is
Although described as an alignment mark for fuse cutting of a redundant bit, the alignment mark of the present invention can be widely applied for laser trimming of a semiconductor device , and is always required.
Not intended to be used only in the fuse cutting redundant bit servant.

[0072]

As described above, the laser trimming of the present invention is performed.
With alignment mark for use and this alignment mark
According to the semiconductor device , at the time of alignment at the time of laser trimming , the target mark at the alignment mark is used.
Make sure that the vertical reflected light intensity differs between the turn and the background.
In other words, since the contrast difference in reflectance can be increased regardless of the thickness of the cover film , the S / N ratio can be improved and accurate positioning can be performed.

[0073] In the method of manufacturing the semi-conductor device of the present invention, it is possible to accurately emit a laser beam to seek a trimming position with high accuracy, not to cause manufacturing defects of the defective therefore the semiconductor device of the trimming.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of an alignment mark according to the present invention, wherein (a) is a plan view and (b) is a cross-sectional view.

FIGS. 2A and 2B are views showing a second embodiment of the alignment mark of the present invention, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is a plan view showing a third embodiment of the alignment mark of the present invention.

FIGS. 4A and 4B are diagrams showing a fourth embodiment of the alignment mark of the present invention, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view.

FIG. 5 is a view showing a fifth embodiment of an alignment mark according to the present invention, wherein (a) is a plan view. (B) is a sectional view.

6A and 6B are diagrams illustrating examples of target patterns of alignment marks according to the present invention, wherein FIG. 6A illustrates an L-shaped target pattern, FIG. 6B illustrates an I-shaped target pattern, FIG. ) Is a cross target pattern.

FIG. 7 is a diagram showing reflectance measurement data of alignment marks of the present invention and a conventional example.

8A and 8B are views showing a sixth embodiment of the alignment mark of the present invention, wherein FIG. 8A is a plan view and FIG. 8B is a sectional view.

FIG. 9 is a diagram showing an example of a very simple circuit of redundant bits.

FIG. 10 is a cross-sectional view of a semiconductor device in which fuses for redundant bits and alignment marks are formed.

FIG. 11 is a diagram showing an example of a target array in a chip.

FIG. 12 is an explanatory diagram of points.

FIG. 13 shows a laser beam using the alignment mark of the present invention.
Ichi構 laser trimming device for use in trimming technology
It is a figure showing an example.

FIG. 14 is a diagram showing a processing procedure from positioning to laser light emission.

FIG. 15 is a diagram showing a processing procedure of X-axis target detection.

[Explanation of symbols]

1, 11, 21, 22, 23, 24, 31 Alignment mark 2 Position detection target 3 Vertical reflectance reduction area 4 Al layer 6 Cover film 8 First PSG layer 8 'Second PSG layer 10 Field oxide film REFERENCE SIGNS LIST 12 substrate 14 Al layer 16 PSG layer 18 vertical reflection area 20 Al layer 26 bit for hole length 27 fuse 30 chip 31 alignment mark 34 laser trimming device 36 laser light source 36 ′ laser light irradiation means 43 XY stage 48 reflectance calculation circuit 49 Arithmetic processing means 50 storage means 51 light source driving means 52 stage driving means

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-260818 (JP, A) JP-A-62-18714 (JP, A) JP-A-58-90728 (JP, A) JP-A-59-1987 225521 (JP, A) JP-A-62-136853 (JP, A) JP-A-56-149445 (JP, U) JP-A-2-92933 (JP, U)

Claims (8)

(57) [Claims] 1. A laser trimming position comprising: a high reflection area for vertically reflecting position detection light; and a low reflection area disposed adjacent to the high reflection area for scattering the position detection light to reduce vertical reflection. In the alignment mark, a first light reflection film that is located in the high reflection area and has a flat surface having a size larger than the spot diameter of the position detection light, and is located in the low reflection area and smaller than the spot diameter. A plurality of second light-reflecting films having a width, the first light-reflecting films covering the first and second light-reflecting films, and a flat surface on the first light-reflecting films; the plurality of second alignment marks laser trimming, characterized in that it comprises a transparency cover film ing and uneven surface corresponding to the unevenness of the light reflecting film. 2. The laser trimming according to claim 1, wherein the plurality of second light reflecting films are formed in a stripe shape extending in a direction perpendicular to a scanning direction of the position detection light. Alignment mark. 3. The alignment mark for laser trimming according to claim 1, wherein said plurality of second light reflecting films are formed in a dot pattern. 4. The alignment mark for laser trimming according to claim 1, wherein said plurality of second light reflecting films are formed in a checkered pattern. 5. The method according to claim 1, wherein the plurality of second light-reflecting films are formed by forming a stripe-shaped reflection film at an upper portion of a stripe-shaped step-forming film. Item 7. A positioning mark for laser trimming according to Item 1. 6. The plurality of second light reflection films are formed by contacting a reflection film having unevenness at a central portion thereof on an upper portion of a dot-shaped film for forming a step. The alignment mark for laser trimming according to claim 1. 7. A high-reflection area that vertically reflects the position detection light and a low-reflection area that is disposed adjacent to the high-reflection area and scatters the position detection light to reduce the vertical reflection. In a semiconductor device having a laser trimming alignment mark in which one of a region and the low reflection region is a target pattern and the other is a background portion, the alignment mark is located in the high reflection region, and the position detection light A first light reflection film having a flat surface having a size larger than the spot diameter; a plurality of second light reflection films located in the low reflection region and having a width smaller than the spot diameter; An uneven surface which covers the second light reflecting film, becomes a flat surface on the first light reflecting film, and corresponds to the unevenness of the plurality of second light reflecting films on the plurality of second light reflecting films. door name Ru transparency of hippopotamus A semiconductor device comprising: the film. 8. A step of forming a fuse portion on the semiconductor substrate, a step of forming a light-reflecting film having a high reflectance in a region other than the fuse portion, and patterning the light-reflecting film to obtain a position detection light. A first light reflecting film having a flat surface having a size larger than the spot diameter, and a plurality of second light reflecting films having a width smaller than the spot diameter;
Forming a light reflecting film on the first light reflecting film and the plurality of second light reflecting films on the first light reflecting film, forming a flat surface on the first light reflecting film, by forming a light reflective layer on the plurality of second concave-convex surface and name Ru transparency cover film corresponding to the irregularities of the light reflection film, the position of the presence area of the first light reflecting layer A step of forming a high-reflection area for vertically reflecting the detection light and a low-reflection area for reducing the vertical reflection by scattering the position detection light, where the plurality of second light reflection films are present; Irradiating the low-reflection region with position detection light substantially vertically, calculating the position of the fuse in the coordinates on the apparatus from the intensity of the vertically reflected light, and irradiating the fuse with laser light to cut the fuse. A method for manufacturing a semiconductor device, comprising: