JP2001267224A - Semiconductor device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, where the position of a mark can be rightly measured even if a process in which an aligning position measuring mark is buried under a metal film is used, and the mark can be accurately aligned with lower layer on the metal film. SOLUTION: A semiconductor device manufacturing method comprises a first process in which a base layer on which a position measuring mark is provided is formed, a second process in which a metal film is formed on the top surface of the base layer, and the metal film is patterned by the use of the position measuring mark, where the position of the position measuring mark provided in the base layer under the metal film is located by the use of waves that penetrate through the metal film, and the metal film is patterned by the use of the mark.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which an alignment mark on an underlayer is used to align the underlayer with a metal layer thereon.

[0002]

2. Description of the Related Art As semiconductor devices have become denser and finer,
The permissible range of displacement between the upper and lower layers has also been reduced.
In addition, in order to improve the operation speed of the semiconductor device by reducing the resistance value of the wiring layer with miniaturization, a method of forming a metal film used for wiring, material, addition of impurities, control of crystallinity,
The method of forming wiring is devised.

FIGS. 9 (a) to 9 (d) and FIGS. 10 (e) to 10 (e)
(G) shows Al reflow sputtering technology, position measurement technology on metal film, exposure technology, reactive ion etching (RI
E) is a sectional process view showing a conventional wiring forming method using the technique.

First, a silicon oxide film 111 is deposited,
The Ti film 112, the A1-Cu alloy film 113, and the Ti film
The films 114 are sequentially formed (FIG. 9A). Next, the wiring layer 1 is formed by ordinary photolithography and etching.
21 (FIG. 9B), and further, an interlayer insulating film 131 is formed.
Is deposited, and necessary planarization is performed (FIG. 9C).

Then, in order to connect the lower wiring and the upper wiring, a via hole 142 is formed by a usual photolithography method and an etching method (FIG. 9D). At this time, a mark portion 141 for adjusting the position of the upper layer wiring and the lower layer wiring is also formed at the same time.

Subsequently, A is formed by reflow sputtering.
The l-Cu film 151 is formed and the via hole 142 is completely filled with Al-Cu (FIG. 10E). At this time, the mark portion 141 utilizes the fact that the filling property of the reflow sputtering method decreases when the opening diameter is large,
Al-Cu on mark portion 141 without completely filling
The depression 152 is left on the film surface.

[0007] Then, when white light (L1 in the figure) is irradiated from above after applying the resist, A
Utilizing the fact that light is irregularly reflected at the depression 152 of the l-Cu film (L2 in the figure), the mark portion 141 is detected from the intensity of the reflected wave, and the lower layer wiring 12, the via hole 142, and the upper layer wiring 171 are detected. Align and perform exposure (Fig. 10
(F)).

After that, if etching is performed by the ordinary reactive ion etching method, the formation of the wiring layer in which the via hole 142 and the upper wiring 171 which have a positional relationship with the lower wiring 121 are simultaneously buried is completed (FIG. 10).
(G)).

[0009]

However, the conventional wiring forming method has the following problems.

When the Al-Cu film 151 is formed by the reflow sputtering method, it is very difficult to control the surface condition on the mark portion 141, and there is a possibility that the large depression 152 of the mark portion 141 is filled. . In particular, when the shape of the via hole is further miniaturized, the degree of filling must be increased, and it becomes impossible to prevent only the mark portion from being filled. In the case of the Al reflow process having such characteristics, it is difficult to specify the position by using the surface state on Al as a mark.

Therefore, visible light, infrared light, and ultraviolet light cannot be transmitted through the metal film and are reflected. However, a sound wave having a long wavelength and an X-ray having a short wavelength are transmitted through the metal film. Thus, it is conceivable to specify the position of the alignment position measurement mark. For example, Japanese Unexamined Patent Publication No. Hei 11-508694 discloses that an impulse beam is irradiated toward a wafer surface to generate an elastic wave in the wafer, and a displacement of the wafer surface generated in response to the elastic wave is detected. A technique for estimating the thickness of a sample by analyzing the time-varying characteristics of an elastic wave in a wafer from the detected displacement by a discrete wave red transform has been disclosed.

However, this publication does not disclose a positioning technique for accurately positioning a metal film with a lower layer on the metal film. Conventionally, there has not been a method of manufacturing a semiconductor device capable of reliably performing the above alignment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. An object of the present invention is to provide a method of embedding a mark position for alignment position using a metal film. Can be measured correctly,
An object of the present invention is to provide a method for manufacturing a semiconductor device, which can surely perform alignment with a lower layer on a metal film.

[0014]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: forming a base layer having a position measurement mark; The method of manufacturing a semiconductor device, comprising: a second step of forming a metal film on the upper surface of the underlayer; and a third step of patterning the metal film using the position measurement mark. The step is characterized in that a position of a position measurement mark in an underlayer of the metal film is specified using a wave transmitted through the metal film, and patterning of the metal film is performed using the position measurement mark. I do.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect of the present invention, the metal film formed in the second step is formed on the surface of the metal film. The structure is such that the shape of the position measurement mark of the underlayer is not maintained.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the metal film formed in the second step may be: It is made of a material that reflects light and transmits sound waves and X-rays.

According to a fourth aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the wave transmitted through the metal film is a sound wave or an X-ray. It is characterized by.

According to a fifth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fourth aspects, the third step includes a step of transmitting through the metal film. The reflected wave of the wave to be measured is measured at a plurality of points to specify the position of the position measurement mark, and the metal film is patterned using the position measurement mark.

According to a sixth aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, the wave transmitted through the metal film is formed of the metal film. Is irradiated with a pulse laser, and is a wave generated by thermal expansion of metal by the pulse laser.

According to a seventh aspect of the present invention, in the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, the wave transmitted through the metal film is shaped like a probe. A wave generated by mechanically hitting the surface of the metal film with a needle having the shape of

According to a eighth aspect of the present invention, there is provided a semiconductor device manufactured by the method for manufacturing a semiconductor device according to any one of the first to seventh aspects.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment FIGS. 1A to 1D and FIGS. 2E to 2G are process diagrams showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention. .

The steps shown in FIGS. 1A to 1D are the same as the steps shown in FIGS. 9A to 9D described above.
That is, first, in the step shown in FIG. 1A, a silicon oxide film 11 is deposited, and a Ti film 12, an A1-Cu alloy film 13, and a Ti film 14 are sequentially formed thereon to form a wiring layer 21. I do. Next, as shown in FIG. 1B, the wiring layer 21 is formed by ordinary photolithography and etching.
To form

On the wafer in this state, an interlayer insulating film 31 is deposited as shown in FIG. Further, in the step shown in FIG. 1D, a via hole 42 is formed by a usual photolithography method and an etching method in order to connect the lower wiring and the upper wiring. At this time, a mark portion 41 for adjusting the position of the upper layer wiring and the lower layer wiring is also formed at the same time.

Next, as shown in FIG.
The Al-Cu film 51 is formed by the sputtering method, and the via hole 42 is completely filled with Al-Cu. At this time, since the mark portion 41 is also completely filled, a depression (see FIG. 10E) on the surface of the Al—Cu film 51 unlike the related art is not formed.

Then, in order to align the lower wiring 21, the via hole 42, and the upper wiring 71 and perform exposure, first,
In the step shown in FIG. 2F, in order to measure the mark portion 41 in which the Al--Cu film 51 is completely embedded, the pulse laser beam R1 is applied by using the mark position detecting device of this embodiment shown in FIG. Irradiate near the mark 41.

As shown in FIG. 3, this mark position detecting device mounts a wafer 2 of this embodiment, which is a sample,
A pulse laser device 3 having a Y stage 1 and irradiating a pulse laser beam R1 to the wafer 2; and a laser beam R2 onto the surface of the wafer 2 through an objective lens 5 to detect a displacement on the surface of the wafer 2. And a detection laser device 4 for irradiation.

The controller 6 controls the driving of the pulse laser device 3 and the detection laser device 4, and a computer 7 for controlling the entire mark position detection operation is connected to the controller 6. The user can perform a predetermined operation with the input device 9 while checking the mark position detection state on the display 8 of the computer 7.

When the wafer 2 is irradiated with the pulse laser beam R1 by using such a mark position detecting device, as shown in FIG.
When the l-Cu film 51 momentarily expands in volume (thermal expansion displacement 50a), a sound wave (thermoelastic wave) S1 is generated. The generated sound wave S1 propagates through the Al-Cu film 51 and is reflected at the interface with the interlayer insulating film 31. When the sound wave S1 reaches the surface of the Al—Cu film 51 again, the surface of the Al—Cu film 51 expands in volume, and the displacement (50b in FIG. With the laser light R2. Then, the depth of the Al—Cu film 51 is estimated by measuring the time from the first sound wave generation to the measurement of the reflected wave.

The same measurement is performed around the mark portion 41 while moving the place little by little. Thereby, the mark portion 41
In the other positions, the time until the reflected wave returns is shortened because the thickness of the Al-Cu film 51 is thin, and the mark portion 41
Then, the position of the mark portion 41 is specified by using the fact that the time becomes long.

Based on the specified mark position information, the uppermost Al-Cu film 51 is processed by ordinary photolithography and etching to form an upper wiring having a structure in which the lower wiring 21 and the via hole 42 are aligned. 71 can be formed.

As described above, in the conventional alignment mark position measurement technique, in order to recognize the mark portion formed on the base as a change in the surface state on the metal film, the metal film is formed such that the recessed portion on the mark is buried. When the film is formed, there is a problem that the mark position cannot be accurately recognized.

On the other hand, in the present embodiment, instead of the change in the surface state of the metal film due to the reflection of light as in the prior art, the reflection at the interface below the metal film is performed by using a wave transmitted through the metal. Since the thickness of the metal film can be measured by observing the wave, the mark portion is deeper than the other portions, so that the mark position can be specified.

As described above, in the present embodiment, the mark portion 41 under the Al-Cu film 51 is utilized not by the light reflected by the metal film but by a sound wave having a long wavelength transmitted through the metal film. To measure the position of
Via holes 42 and mark portions 41 as in the Al process
Even when a process of embedding is used with a metal film, the position of the alignment position measurement mark 41 can be accurately specified, and the accuracy of the alignment deviation can be significantly improved.

[Second Embodiment] FIGS. 5A and 5B and FIGS. 6A and 6B are process diagrams showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention. In the manufacturing method of the first embodiment, only different parts are shown.

In the manufacturing method of this embodiment, the steps shown in FIGS. 1A to 1D are performed in the same manner as in the manufacturing method of the first embodiment, and thereafter, the following steps are performed. become.

That is, after the via hole 42 and the mark portion 41 are simultaneously formed in the step shown in FIG.
In step (a), a W (tungsten) film 75 is formed on the wafer surface, and is deposited so as to completely fill the via hole 42 and the mark portion 41 with a W film for plug formation.

In the subsequent step shown in FIG.
(Chemical Mechanical Poli
shing method or CDE (Chemical D)
The W film 75 is flattened by the (ry Etching) method until it reaches the upper surface of the interlayer insulating film 31.

Thereafter, in the step shown in FIG.
After depositing the Cu film 51A (thickness: 1 μm or more), in order to detect the alignment position mark 41, the surface of the wafer is irradiated with pulsed laser light R1 by the mark position detection device of FIG. However, when the mark portion 41 and the via hole 42 are buried with W plugs 75a and 75b, respectively, the Al-Cu film 51 is included in other portions including the mark portion 41.
There is no change in the film thickness of A.

As the sound wave travels at a speed corresponding to the density of the film, the sound wave traveling in the Al travels through the SiO2 and reflects at the Si interface where it is not a mark portion, and travels through the W at the mark portion. It is reflected at the SiO2 interface. Since there is a difference in the time required for the reflected wave to return to the Al surface, the W mark portion can be recognized.

As described above, even in a structure formed of a plurality of types of metal films, the mark position is specified by measuring the reflected wave at a plurality of points on the wafer based on the difference in the return time of the reflected wave. I can do things.

[Third Embodiment] FIGS. 7 (a) and 7 (b)
It is an image figure showing the detecting method of the alignment position measurement mark performed by the manufacturing method of the semiconductor device concerning a 3rd embodiment of the present invention. FIG. 8 is a configuration block diagram of a mark position detection device used in the present embodiment.

In the present embodiment, as shown in FIG. 7A, the thermal expansion of the metal film by the laser beam is not used as the sound wave source as in the first and second embodiments. Using a probe-shaped fine needle 81, a sound wave S2 is generated by mechanically tapping the wafer surface, and as shown in FIG. 7B, a displacement 50c of the surface of the Al—Cu film 51A due to the reflected wave is generated. Is observed by the laser R2 in the same manner as in the first and second embodiments, and the position of the alignment position measurement mark is detected.

As shown in FIG. 8, the mark position detecting device used in the present embodiment has a structure in which a probe driving device 80 in which the pulse laser device 3 is replaced in the structure of FIG.

Even with the structure as in this embodiment, the same effects as those of the first and second embodiments can be obtained.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the metal film of the wiring layer 51 is not limited to the Al-Cu film, but may be Cu, A
Similar effects can be obtained by using g, Au, W, Pt, Ru, and other metal alloys. Also, the wave used for the measurement is not limited to a sound wave, and the same effect can be obtained as long as the wave transmits through a metal film such as X-ray.

[0048]

As described in detail above, according to the present invention, instead of observing the surface state of the metal film by the reflection state of light as in the prior art, a wave transmitted through the metal is used. Since the thickness of the metal film can be measured by observing the reflected wave at the interface below the metal film, the position of the alignment position measurement mark is different from that of the other portions. The position of the measurement mark can be specified.

Therefore, even when a process in which the via hole and the position measurement mark are buried with a metal film such as a reflow / Al process is used, the position of the alignment position measurement mark is accurately specified. Accordingly, the accuracy of misalignment between the base layer and the metal film as the upper layer can be significantly improved.

Further, even when a substance having the property of strongly reflecting sound waves is used as a structure indicating the position of the alignment position measurement mark, the reflected waves can be measured at multiple points on the metal film. It is possible to accurately specify the position of the position measurement mark.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process drawing following FIG. 1;

FIG. 3 is a configuration block diagram of a mark position detection device according to the first embodiment.

FIG. 4 is an image diagram showing a mark position detection operation according to the first embodiment.

FIG. 5 is a process chart showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention.

FIG. 6 is a process drawing following FIG. 5;

FIG. 7 is an image diagram showing a method of detecting alignment position measurement marks, which is performed in a method of manufacturing a semiconductor device according to a third embodiment of the present invention.

FIG. 8 is a configuration block diagram of a mark position detection device used in the present embodiment.

FIG. 9 is a process chart showing a conventional method for manufacturing a semiconductor device.

FIG. 10 is a process drawing following FIG. 9;

[Explanation of symbols]

 Reference Signs List 11 silicon oxide film 12 Ti film 13, 51 A1-Cu alloy film 14 Ti film 21 lower layer wiring 31 interlayer insulating film 41 position measurement mark 42 via hole 71 upper layer wiring R1 pulse laser beam R2 detection laser beam S1 sound wave (thermoelastic wave) S2 elastic wave

Continuation of the front page F term (reference) 5F033 HH09 JJ01 JJ09 JJ19 KK09 KK18 PP18 QQ01 QQ11 QQ37 QQ48 XX00 5F046 EA12 EA18 EA19 EB01 EB05 FA05 FA08 FA20

Claims (8)

[Claims] A first step of forming a base layer having a mark for position measurement, a second step of forming a metal film on an upper surface of the base layer, and the step of forming a metal film using the mark for position measurement. A third step of patterning a film, the third step comprising: using a wave transmitted through the metal film to position a position measurement mark in an underlayer of the metal film. And patterning the metal film using the position measurement mark. 2. The semiconductor according to claim 1, wherein the metal film formed in the second step has a structure on a surface thereof different from a shape of a position measurement mark of the underlayer. Device manufacturing method. 3. The metal film formed in the second step is made of a material that reflects light and transmits sound waves and X-rays. The manufacturing method of the semiconductor device described in the above. 4. The method according to claim 1, wherein the wave transmitted through the metal film is a sound wave or an X-ray. 5. The method according to claim 3, wherein the position of the position measurement mark is determined by measuring a reflected wave of the wave transmitted through the metal film at a plurality of points, and using the position measurement mark. 2. The patterning of a metal film is performed.
A method for manufacturing a semiconductor device according to claim 4. 6. The wave transmitted through the metal film is a wave generated by irradiating a pulse laser to the metal film and generating thermal expansion of the metal by the pulse laser. The method for manufacturing a semiconductor device according to any one of the above. 7. The wave transmitted through the metal film is a wave generated by mechanically hitting the surface of the metal film with a probe having a probe-like shape. Item 5
The method for manufacturing a semiconductor device according to any one of the above. 8. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 1.