TWI629726B - Semiconductor element, sputtering target and semiconductor device - Google Patents

Abstract

It can improve the reliability of the electrode film under high temperature environment.

The semiconductor element (20) has an electrode film (21) mainly composed of aluminum. In this electrode film (21), second phase particles containing aluminum and metal added to aluminum are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more. The electrode film (21) of such a semiconductor element (20) is precipitation hardened and becomes strong. Therefore, the stress-migration of the electrode film (21) under a high-temperature environment is suppressed, the heat-resistant cycle characteristics are improved, and the reliability is improved. Therefore, the semiconductor element (20) including such an electrode film (21) also improves reliability and improves life.

Description

Semiconductor element, sputtering target and semiconductor device

The present invention relates to semiconductor elements, sputtering targets and semiconductor devices.

The semiconductor element in a high-temperature environment generates thermal stress in the electrode film formed on the element. In particular, in a micronized electrode film containing aluminum as a main component, thermal stress may cause deterioration (stress migration) such as transposition, voids, and wire breakage. The electrode film that causes stress migration can cause circuit breakage and short circuit of the semiconductor element.

As a means for suppressing stress migration, there is a technique of adding a trace amount of metal to the electrode film. This technique can suppress the displacement of the electrode film and improve the strength of the electrode film. Generally, 0.1 wt% to 2 wt% of copper or nickel is used as the metal added to the electrode film made of aluminum.

In addition, as another method, there is a technique of forming a metal film (barrier film) of titanium, nickel, gold, or the like on the surface of the electrode film (for example, refer to Patent Document 1). With this technique, in the electrode film where the barrier film is formed on the surface, since the diffusion of atoms constituting the electrode film under a high-temperature environment is suppressed, the occurrence of stress migration of the electrode film can be suppressed.

[Advanced technical literature] [Patent Literature]

[Patent Document 1] Japanese Unexamined Patent Publication No. 11-186263

However, as a method of adding a trace amount of metal to the electrode film, for example, the reliability test of an electrode film containing copper (0.5wt%) or nickel (1wt%) for aluminum containing 1wt% of silicon is actually carried out, according to this test As a result, thermal stress was generated in the electrode film in a high-temperature environment, and it was confirmed that stress migration occurred.

In addition, in the method of forming the barrier film on the electrode film, in order to form, the manufacturing process increases and the manufacturing cost becomes high.

According to one aspect of the present invention, it is possible to provide a semiconductor device having an electrode film which contains aluminum as a main component and contains the aluminum and an additive metal which is added to the aluminum and has a smaller diffusion coefficient than nickel The second phase particles are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more.

Furthermore, according to one aspect of the present invention, it is possible to provide a semiconductor element having an electrode film which contains aluminum as a main component and contains the aluminum and is added to the aluminum in an amount of 1 wt% or more and 40 wt% or less The second phase particles of manganese are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more.

Furthermore, according to one aspect of the present invention, it is possible to provide a sputtering target material using aluminum as a main component for forming an electrode film on such a semiconductor device by a sputtering method.

Moreover, according to one aspect of the present invention, a semiconductor device including such a semiconductor element can be provided.

According to the disclosed technology, the reliability of the electrode film in a high-temperature environment can be improved.

The above and other objects, features, and advantages of the present invention can be clearly understood from the following description related to the accompanying drawings, which show preferred embodiments as examples of the present invention.

10‧‧‧Semiconductor device

11‧‧‧Insulated substrate

12,13‧‧‧Metal foil

14‧‧‧Solder layer

15‧‧‧bond wire

20‧‧‧Semiconductor components

21, 22‧‧‧ electrode film

21a‧‧‧Second phase particles

23‧‧‧Stacked film

30, 30a‧‧‧ like

FIG. 1 is a diagram showing an example of a semiconductor device in which semiconductor elements are arranged according to the first embodiment.

2 is a diagram showing an example of a hardware configuration of an analysis device for analyzing an electrode film of a semiconductor element according to the first embodiment.

3 is a diagram showing an example of an image taken by a transmission electron microscope of an electrode film formed on a semiconductor element according to the first embodiment.

4 is a graph showing the number of particles, diameter, and area ratio of second-phase particles with respect to the amount of metal (nickel) added to the electrode film in the first embodiment.

5 is a diagram showing an example of an SEM image of the surface of the electrode film per cycle number in the thermal cycle test in the first embodiment.

6 is a graph showing the number of heat-resistant cycles relative to the amount of metal (nickel) added to the electrode film in the first embodiment.

7 is a graph showing the number of particles, diameter, and area ratio of second-phase particles with respect to the amount of metal (manganese) added to the electrode film in the second embodiment.

8 is a diagram showing an example of the SEM image of the surface of the electrode film per cycle number in the thermal cycle test in the second embodiment.

9 is a graph showing the number of heat-resistant cycles with respect to the amount of metal (manganese) added to the electrode film in the second embodiment.

The semiconductor element is an electrode film having aluminum as a main component. In this electrode film, the second phase particles containing aluminum and the metal added to aluminum are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more. The electrode film of such a semiconductor element has improved heat-resistant cycle characteristics, and the life of the semiconductor element is improved.

In the first embodiment, a semiconductor element having the above-mentioned electrode film using nickel as an additive metal will be specifically described.

[First Embodiment]

The semiconductor device on which the semiconductor element is mounted will be described using FIG. 1.

FIG. 1 is a diagram showing an example of a semiconductor device in which semiconductor elements are arranged according to the first embodiment.

1(A) is a side view showing the semiconductor device 10, and FIG. 1(B) is a side view showing an enlarged main part of the semiconductor element 20 included in the semiconductor device 10.

As shown in FIG. 1(A), the semiconductor device 10 includes: an insulating substrate 11 on which a patterned metal foil 12, 13 is formed on the main surface; and The semiconductor element 20 is mounted on the metal foil 12 via the solder layer 14.

As shown in FIG. 1(B), the semiconductor element 20 has electrode films 21 and 22 formed on its main surface (front and back), respectively. The electrode film 21 of the semiconductor element 20 and the metal foil 13 of the insulating substrate 11 are electrically connected by bonding wires 15.

Next, the method of forming the electrode films 21 and 22 will be described.

A sputtering target is used to adjust the composition ratio of aluminum that adjusts the main component of the electrode film 21 to the metal added to the aluminum.

First, the composition of this sputtering target will be explained.

In order to prevent the mutual diffusion of the contact parts of aluminum and silicon wafers, silicon is added to aluminum. If this addition amount is too small, the effect will not appear, so at least 0.1 wt% of silicon needs to be added. On the other hand, if the amount of silicon added is too large, there is a possibility that the electrical conduction at the contact portion may deteriorate. Therefore, the amount of silicon added needs to be 5 wt% or less. When such silicon is actually added, it is preferably 0.5 wt% or more and 2 wt% or less.

In addition, in order to suppress stress migration, it is necessary to suppress the movement of crystal grain boundaries. Therefore, 5wt%~40wt% nickel is added.

Since the sputtering target contains impurities, in the film formation using the sputtering target, the impurities will be scattered throughout the chamber, and there is a possibility that the inside of the chamber may be contaminated. In order to suppress the contamination caused by such impurities, it is preferable that the total amount of impurities in aluminum excluding the added elements is 100 ppm or less, and more preferably 10 ppm or less.

The sputtering target of such composition is made by semi-continuous casting method or powder metallurgy Gold method to make. In addition, after the aluminum block is produced by these methods, plastic processing and heat treatment such as rolling and forging may be performed for shaping of the shape or control of the crystal structure.

Next, the film formation process using the above sputtering target will be described.

For example, the composition ratio of nickel added to aluminum containing 1 wt% of silicon is set to 0.2 wt%, 1 wt%, 5 wt%, and 10 wt%. Four kinds of sputtering targets constituted with such a composition ratio are prepared in advance. The silicon wafer subjected to the oxidation treatment is heated, and an electrode film with a thickness of 5 μm is formed on the surface of the heated silicon wafer by a sputtering method using each target.

A protective film is formed on the electrode film formed on the surface of the silicon wafer, a back surface polishing process is performed on the back surface of the silicon wafer, and an electrode film is formed on the back surface after the process. The electrode film is formed using a vapor deposition method or a sputtering method. In addition, the electrode film is made of aluminum, titanium, nickel, gold, or the like.

The silicon wafers with the electrode films formed on the front and back surfaces were subjected to a heat treatment at 420° C. for 80 minutes and then chipped to form a semiconductor element 20 having electrode films 21 and 22.

An analysis device for analyzing the electrode films 21 and 22 of the semiconductor element 20 thus formed will be described using FIG. 2.

2 is a diagram showing an example of a hardware configuration of an analysis device for analyzing an electrode film of a semiconductor element according to the first embodiment.

The analysis device 100 includes a control unit 110, a display unit 120, an input unit 130, and an electron microscope unit 140.

The control unit 110 controls the entire analysis device 100. For example, the electron microscope unit 140, which will be described later, is controlled to observe and image the observation object, so that The captured image is displayed on the display unit 120. In addition, the control unit 110 executes the image processing of the image captured by the electron microscope unit 140. By image processing, the diameter and area of specific crystal grains and the like are calculated from the image. The control unit 110 also performs processing necessary for analysis.

Such a control unit 110 further includes a CPU (Central Processing Unit) 110a, a RAM (Random Access Memory) 110b, an HDD (Hard Disk Drive) 110c, a graphics processing unit 110d, and an input/output interface 110e. Each of these parts is connected to a signal through the bus 110f to be input and output.

The CPU 110a comprehensively controls the entire computer by executing various programs stored in a storage medium such as the HDD 110c.

The RAM 110b temporarily stores at least a part of the program to be executed on the CPU 110a and various data necessary for processing the program.

The HDD 110c stores programs executed by the CPU 110a and various data necessary for the execution.

The graphics processing unit 110d is connected to a display unit 120 described later. The graphics processing unit 110d displays the portrait on the display screen of the display unit 120 in accordance with a command from the CPU 110a.

The input/output interface 110e connects the input unit 130 and the electron microscope unit 140 described later. The I/O interface 110e transmits the input signal from the input unit 130 to the CPU 110a via the bus 110f. The I/O interface 110e notifies the electron microscope unit 140 of the imaging control signal from the CPU 110a via the bus 110f. Furthermore, the input/output interface 110e displays the image taken from the electron microscope section 140 via the bus 110f The signal is sent to the CPU 110a.

The display unit 120 is a display device such as a display or a monitor. The display unit 120 can display an image of an observation object captured by the electron microscope unit 140 described later, an analysis result, and the like based on image information from the CPU 110a.

The input unit 130 is an input device such as a keyboard or a mouse. The input unit 130 notifies the CPU 110a by accepting the setting of observation conditions, input information for performing observation, and the like through operation input by the user.

The electron microscope unit 140 is, for example, an electron microscope such as a transmission electron microscope (TEM: Transmission Electron Microscope) or a scanning electron microscope (SEM: Scanning Electron Microscope). The electron microscope unit 140 performs observation and imaging of the observation target object set at a predetermined position based on the imaging control signal transmitted from the control unit 110. In addition, the electron microscope unit 140 transmits the imaging information of the set observation object to the control unit 110.

Next, the imaging results of the electrode film 21 of the semiconductor element 20 of such an analyzer 100 will be described using FIG. 3.

3 is a diagram showing an example of an image taken by a transmission electron microscope of an electrode film formed on a semiconductor element according to the first embodiment.

FIG. 3(A) is an image 30 showing a cross section of the semiconductor element 20 taken using TEM as the electron microscope section 140. In addition, the semiconductor element 20 is formed with an electrode film 21 and is heated (annealed). The electrode film 21 is made by adding 1 wt% of nickel to aluminum containing 1 wt% of silicon.

In addition, FIG. 3(B) is an enlarged image of the dotted area in FIG. 3(A) 30a.

In addition, according to the image 30, as shown in FIG. 3(A), a deposition film 23 is arranged on the electrode film 21. When observing the semiconductor element 20 by TEM, a deposition film 23 is arranged on the electrode film 21 of the semiconductor element 20, and the semiconductor element 20 is processed to obtain a cross section of the semiconductor element 20. This deposited film 23 prevents excessive cutting of the cross-section of the processed semiconductor element 20.

According to the images 30 and 30a shown in FIGS. 3(A) and (B), it can be confirmed that the second phase particles 21a (aluminum nickel (Al ₃ Ni)) containing aluminum and nickel in the electrode film 21 will Precipitate. In addition, the shape of the second phase particles 21a is substantially equivalent to a circle, and the diameter thereof is approximately 10 nm to 50 nm.

Next, the number of particles of the second phase particles 21a per 1 μm ² of the electrode film 21 with respect to the amount of nickel added, the diameter of the circle equivalent to the second phase particles 21a, and the second phase particles 21a will be described using FIG. 4. Area (area rate).

4 is a graph showing the number of particles, diameter, and area ratio of second-phase particles with respect to the amount of metal (nickel) added to the electrode film in the first embodiment.

FIG. 4(A) shows the number of particles of the second phase particles, FIG. 4(B) shows the diameter, and FIG. 4(C) shows the graph of the area ratio.

In addition, the horizontal axis in FIG. 4 indicates the amount of added nickel (wt%). The vertical axis is related to the second phase particles 21a. FIG. 4(A) shows the number of particles (number/μm ² ), FIG. 4(B) shows the diameter (μm), and FIG. 4(C) shows the area ratio ( %).

The analysis device 100 performs image processing on the image 30 (FIG. 3) of the amount of nickel taken in the TEM, and specifies the second phase particles 21 a deposited on the electrode film 21 based on the black and white density in the image 30. Then, the analysis device 100 performs image processing, and counts the number of particles of the specified second phase particles 21a. The analysis device 100 calculates the number of particles of the second phase particles 21 a per 1 μm ² of the electrode film 21 by dividing the counted number of particles by the cross-sectional area of the electrode film 21.

According to the graph of FIG. 4(A) showing the number of particles of the second phase particles 21a, it can be seen that the second phase particles 21a are dispersed and deposited in the electrode film 21 under the addition of nickel. As the amount of nickel added to the electrode film 21 increases to 0.2 wt%, 1 wt%, and 5 wt%, the number of particles of the second phase particles 21a increases. When the amount of nickel added is 10 wt%, the number of particles is roughly maintained at 8 wt%.

Next, the analysis device 100 performs image processing, respectively measures the diameter of the specific second-phase particles 21a that corresponds to a circle, and calculates the average value of the diameters.

As shown in FIG. 4(B), the diameter of the second phase particles 21a increases as the amount of nickel added increases, and it can be said that the area of the second phase particles 21a per one increases.

The analysis device 100 calculates the area of each second phase particle 21a based on the amount of nickel added from the result of FIG. 4(B). In addition, the analysis device 100 calculates the area of the second phase particles 21a from the product of the area of each second phase particle 21a and the total number of particles of the second phase particles 21a counted in FIG. 4(A). total. Furthermore, the analysis device 100 The ratio (area ratio) of the total area of the second phase particles 21 a to the cross-sectional area of the electrode film 21 is calculated by dividing the total area of the second phase particles 21 a by the cross-sectional area of the electrode film 21.

From the graph of FIG. 4(C), it can be seen that the area ratio of the second-phase particles 21a thus calculated increases as the amount of nickel added to the electrode film 21 increases, and the area occupied by the second-phase particles 21a increases.

As described above, as the amount of nickel added to the electrode film 21 increases, and the area ratio of the second phase particles 21a increases, precipitation hardening occurs in the electrode film 21 and the electrode film 21 becomes strong. In addition, in order to make the electrode film 21 stronger, it is necessary to precipitate the second phase particles 21a in the electrode film 21 to be finely and uniformly dispersed. In order to cause such precipitation hardening to occur in the electrode film 21, for example, there is a method of forming the heating temperature of the silicon wafer at the time of forming the electrode film 21 by a sputtering method to 300° C. to 27° C. (room temperature).

Next, the thermal cycle test performed on the electrode film 21 that precipitates the second phase particles 21a according to the amount of nickel added will be described.

In the thermal cycle test, a dummy wafer (9 mm in length×9 mm in width×0.5 mm in thickness) made of silicon forming each electrode film 21 (film thickness 5 μm) was heated from -55° C. to 250° C. for 10 minutes. It takes 10 minutes to cool from 250℃ to -55℃. In the thermal cycle test, this is set to 1 cycle, every 100 cycles up to 100 cycles, every 100 cycles from 100 cycles to 500 cycles, then 800 cycles, 1000 cycles, the analysis device 100 will use SEM as the electron The microscope section 140 observes the deteriorated form of the surface of the electrode film 21.

FIG. 5 is used to explain the electrode film 21 when 1 wt% of nickel is added SEM image as an example of the SEM observation results.

5 is a diagram showing an example of an SEM image of the surface of the electrode film per cycle number in the thermal cycle test in the first embodiment.

5(A) to (D) are SEM images showing the 0 cycle (initial state), 30 cycle, 40 cycle, and 300 cycle of the thermal cycle test, respectively.

First, as shown in FIG. 5(A), the surface of the electrode film 21 in the initial state before the thermal cycle test is composed of polycrystals of each crystal of aluminum, silicon, and nickel.

Once such electrode film 21 is subjected to a thermal cycle test, due to the difference in the linear expansion coefficient of silicon and aluminum (approximately 20 ppm/°C) of the semiconductor element, the aluminum crystal with low yield stress will repeatedly expand and contract, and this crystal is applied stress. At 30 cycles, the grain boundaries where the bonding of each crystal is weak, as shown in FIG. 5(B), will appear at the grain boundaries.

Next, at the 40th cycle, since the crystal grain boundaries floated and the grain boundaries received stress with each other, as shown in FIG. 5(C), irregularities occurred on the surface where the aluminum crystal jumped out, resulting in the surface of the electrode film 21 Membrane degradation.

In addition, in the thermal cycle test of the first embodiment, as described above, from 0 cycles to 100 cycles, every 10 cycles, from 100 cycles to 500 cycles, and every 100 cycles, SEM observation was performed. Therefore, when film degradation is observed at 40 cycles, the film degradation of the surface occurs from 30 cycles to 40 cycles previously observed, and the number of heat-resistant cycles at which the film degradation of the surface is 30 cycles is assumed.

The electrode film 21 at this time is a film inferior even if unevenness occurs on the surface Also, because the bonding between the crystals is maintained, current can flow.

Furthermore, at 300 cycles, each crystal escapes to the point where the stress is the smallest in order to relax the stress received, so the bonding of the crystal grain boundaries is weak. Finally, as shown in FIG. 5(D), cracks enter the crystal grain boundary, the crystals are separated from each other, and the film degradation of the grain boundary of the electrode film 21 occurs. At this time, the precipitates existing in the crystal grain boundaries and the crystal grains are aggregated, and without moving the crystal grain boundaries, the crystal jumps out and stress migration occurs.

Therefore, in the thermal cycle test of the first embodiment, the film degradation of the grain boundary of the electrode film 21 was observed at 300 cycles, so the film degradation of the grain boundary occurred between 200 cycles and 300 cycles observed in the previous one. Therefore, the number of heat-resistant cycles in which the film at the grain boundary deteriorates is set to 200 cycles.

At this time, if the electrode film 21 is a film that is cracked at the grain boundary, the electrons cannot move between the crystals, and the current hardly flows. Therefore, in the first embodiment, the electrode film 21 is an improvement in the number of heat-resistant cycles for deteriorating the film on the surface before the current cannot flow.

The electrode film 21 at the addition amount of nickel of 0.2 wt%, 5 wt%, and 10 wt% was also subjected to a thermal cycle test, and the surface observation of the electrode film 21 of the SEM was performed in the same manner as described above. Although the display of these SEM images is omitted, the heat resistance cycle number of the surface observation result of the electrode film 21 according to the addition amount of nickel is 0.2 wt%, 1 wt%, 5 wt%, and 10 wt% will be described using FIG. 6.

6 is a graph showing the number of heat-resistant cycles relative to the amount of metal (nickel) added to the electrode film in the first embodiment.

In addition, FIG. 6 is a horizontal axis showing the addition amount (wt%) of nickel, and a vertical axis is a table The graph shows the number of heat-resistant cycles (cycles) showing the number of cycles in which film deterioration has occurred. In addition, the circle symbol (◯) indicates the number of cycles of film degradation on the surface of the electrode film 21, and the solid line is a graph obtained from the circle symbol. The square symbol (□) indicates the number of cycles in which the film degradation of the crystal grain boundary of the electrode film 21 occurs, and the dotted line indicates the graph obtained from the square symbol.

According to these two types of graphs, as the amount of nickel added increases, the number of heat-resistant cycles also increases. As illustrated in FIG. 4, it is conceivable that as the amount of nickel added to the electrode film 21 increases, the electrode film 21 is precipitated and hardened, and the electrode film 21 becomes stronger, and the heat-resistant cycle characteristics are improved.

In particular, when the added amount is 0.2 wt% and 1 wt%, the number of heat-resistant cycles with respect to the same hardly changes, but if it is 5 wt% or more, the number of heat-resistant cycles will increase. Therefore, it is conceivable that the addition amount of nickel is preferably 5 wt% or more. In addition, according to the graph of FIG. 4, it can be seen that the second phase particles 21 a with the added amount of 5 wt% or more are dispersed and precipitated, and the area ratio of the area thereof is 15% or more. Therefore, in order to improve the number of heat-resistant cycles of the electrode film 21, it is preferable that the second phase particles 21a of the electrode film 21 are dispersed and precipitated, and the area ratio is 15% or more.

When considering the application of the semiconductor element 20, in order for the semiconductor element 20 to withstand an operating temperature of 150°C to 175°C, the number of heat-resistant cycles needs to be at least 200 cycles. In order to satisfy such requirements, it is preferable that the amount of nickel added to the electrode film 21 is 10 wt% or more. In addition, according to the graph of FIG. 4, the area ratio of the second phase particles 21 a whose addition amount is 10 wt% or more is 30% or more.

Moreover, according to Patent Document 1, when an electrode film containing aluminum not added with nickel as a main component actually forms a nickel barrier film, the surface of the electrode film The number of heat-resistant cycles of film degradation is about 500 cycles. Therefore, from the graph shown in FIG. 6, in order to obtain a heat resistance cycle number equal to or higher than that of the barrier film, the amount of nickel added to the electrode film 21 needs to be 18 wt% or more.

However, if the amount of nickel added to the electrode film 21 exceeds 40% by weight, the area ratio of the second phase particles 21a of the electrode film 21 will increase. Therefore, the ultrasonic and The risk of breaking the circuit of the semiconductor element 20 under the load is increased. Therefore, it is preferable that the amount of nickel added is 40 wt% or less.

In addition, suppressing the occurrence of stress migration in this way depends on the diffusion state of nickel in aluminum. Therefore, as long as the metal has a diffusion coefficient smaller than that of nickel, it can help suppress the occurrence of stress migration as in the case of nickel. For such a metal, for example, zirconium, iron, or palladium can be used instead of nickel.

In the electrode film 21 of the semiconductor element 20, nickel is added to aluminum as a main component, and the second phase particles 21a containing this nickel are dispersed and precipitated, and the area ratio of the second phase particles 21a is 15% or more. In addition, the amount of nickel added at this time is 5 wt% or more and 40 wt% or less. Thereby, since precipitation hardening occurs in the electrode film 21, it is not necessary to form a barrier film, and the heat-resistant cycle characteristics of the electrode film 21 can be improved. Therefore, in the semiconductor element 20 having such an electrode film 21, the occurrence of stress migration of the electrode film 21 in a high-temperature environment is suppressed, reliability is improved, life is extended, and an increase in manufacturing cost can be suppressed.

[Second Embodiment]

The second embodiment describes the use of manganese as the first embodiment. In the case of adding metal to the electrode films 21 and 22 of the semiconductor device 10.

First, the composition of this sputtering target will be explained.

In order to prevent the mutual diffusion of the contact parts of aluminum and silicon wafers, silicon is added to aluminum. If this addition amount is too small, the effect will not appear, so at least 0.1 wt% of silicon needs to be added. On the other hand, if the amount of silicon added is too large, there is a possibility that the electrical conduction at the contact portion may deteriorate. Therefore, the amount of silicon added needs to be 5 wt% or less. When such silicon is actually added, it is preferably 0.5 wt% or more and 2 wt% or less.

In addition, in order to suppress stress migration, it is necessary to suppress the movement of crystal grain boundaries. Therefore, 1wt%~40wt% manganese is added.

Since the sputtering target contains impurities, in the film formation using the sputtering target, the impurities will be scattered throughout the chamber, and there is a possibility that the inside of the chamber may be contaminated. In order to suppress the contamination caused by such impurities, it is preferable that the total amount of impurities in aluminum excluding the added elements is 100 ppm or less, and more preferably 10 ppm or less.

The sputtering target with such a composition is produced by a semi-continuous casting method or a powder metallurgy method. In addition, after the aluminum block is produced by these methods, plastic processing and heat treatment such as rolling and forging may be performed for shaping of the shape or control of the crystal structure.

Next, the film formation process using the above sputtering target will be described.

The electrode films 21 and 22 of the second embodiment are formed on the surface of an oxidized silicon wafer by a sputtering method using three kinds of sputtering targets (film thickness is 5 μm), and the three kinds of sputtering The shooting target material is 1wt%, 4wt%, 9wt% to constitute the composition ratio of manganese added to aluminum containing 1wt% silicon. Such as This creates a semiconductor element 20 having electrode films 21 and 22 to which manganese is added (see FIG. 1).

The analysis apparatus 100 uses TEM, and observes the cross section of the electrode film 21 of the semiconductor element 20 as in the first embodiment. The analysis device 100 performs image processing on the image observed in TEM, and specifically precipitates aluminum and manganese-containing second phase particles (aluminum-manganese (Al ₆ Mn), aluminum-manganese-silicon (α-AlMnSi)) deposited on the electrode film 21 . In addition, as in the first embodiment, the analysis device 100 counts the number of particles of the second phase particles from the image of each added amount of manganese, and calculates the average value and area ratio of the diameters of the second phase particles, respectively.

The number of particles of the second phase particles per 1 μm ² of the electrode film 21 thus obtained with respect to the addition amount of manganese, the diameter of the circle corresponding to the second phase particles, and the area of the second phase particles will be described using FIG. 7. rate.

7 is a graph showing the number of particles, diameter, and area ratio of second-phase particles with respect to the amount of metal (manganese) added to the electrode film in the second embodiment.

FIG. 7(A) shows the number of particles of the second phase particles, FIG. 7(B) shows the diameter, and FIG. 7(C) shows the graph of the area ratio.

The horizontal axis of FIG. 7 represents the amount of added manganese (wt%). In addition, the vertical axis is related to the particles of the second phase, FIG. 7(A) shows the number of particles (number/μm ² ), FIG. 7(B) shows the diameter (μm), and FIG. 7(C) shows the area ratio (% ).

According to the graph of FIG. 7(A), it can be seen that the second phase particles of the second embodiment are also dispersed and precipitated in the electrode film 21 under the addition of manganese. In the case of the second embodiment, as the amount of manganese added to the electrode film 21 increases For 1wt%, 4wt%, 9wt%, the number of particles of the second phase particles will be reduced.

As shown in FIG. 7(B), the diameter of the second-phase particles increases as the amount of manganese added increases, and it can be said that the area of the second-phase particles per one increases.

As shown in the graph of FIG. 7(C), the area ratio of the second phase particles increases as the amount of manganese added to the electrode film 21 increases, and the area occupied by the second phase particles increases.

As described above, as the amount of manganese added to the electrode film 21 increases, the area ratio of the second-phase particles increases. In the second embodiment, precipitation hardening occurs in the electrode film 21, which can be said to be strong.

Next, the thermal cycle test performed on the electrode film 21 that precipitates the second phase particles according to the addition amount of manganese as described above will be described.

The thermal cycle test of the second embodiment was also carried out under the same conditions and methods as the thermal cycle test of the first embodiment, and the deterioration state of the surface of the electrode film 21 was observed by SEM every cycle. However, in the thermal cycle test of the second embodiment, the electrode film 21 per 100 cycles is observed by SEM between 0 cycles and 3000 cycles.

The SEM image of the electrode film 21 when 9 wt% of manganese is added will be described using FIG. 8 as an example of the SEM observation result.

8 is a diagram showing an example of the SEM image of the surface of the electrode film per cycle number in the thermal cycle test in the second embodiment.

8(A) to (C) are SEM images showing the 0 cycle (initial state), 2300 cycle, and 2600 cycle of the thermal cycle test, respectively.

The surface of the electrode film 21 in the initial state before the thermal cycle test As shown in FIG. 8(A), polycrystals are composed of crystals of aluminum, silicon, and manganese.

Once a thermal cycle test is performed on such an electrode film 21, as in the first embodiment, due to the difference in the linear expansion coefficients of silicon and aluminum of the semiconductor element, the aluminum crystal with low yield stress will repeatedly expand and contract. Apply stress. At the 2300 cycle, the grain boundaries where the bonding of each crystal is weak, as shown in FIG. 8(B), will start to appear.

Next, at the 2600 cycle, since the crystal grain boundaries floated, and the grain boundaries received stress with each other, as shown in FIG. 8(C), unevenness occurred on the surface where the aluminum crystal ran out, and the surface of the electrode film 21 occurred The film deteriorates.

At this time, the electrode film 21 is as described above, and even if the film degradation occurs on the surface, the bonding between the crystals is maintained, so that a current can flow.

After that, a thermal cycle test was performed up to 3000 cycles. At 3000 cycles, no degradation of the film at the grain boundary of the electrode film 21 occurred.

Therefore, in the thermal cycle test of the second embodiment, the film degradation on the surface of the electrode film 21 was observed at 2,600 cycles, so the film degradation on the surface occurred from 2,500 cycles to 2,600 cycles observed before. Therefore, the number of heat-resistant cycles in which the film on the surface deteriorates is 2500 cycles.

In addition, in the thermal cycle test of the second embodiment, the film degradation of the grain boundary of the electrode film 21 was not observed even after 3000 cycles. Therefore, the number of heat-resistant cycles of the film degradation of the grain boundary can be said to be 3000 cycles or more.

Except when the amount of manganese is 9wt%, about 1wt%, 4wt% The electrode film 21 at that time was also subjected to a thermal cycle test, and the surface of the electrode film 21 of the SEM was observed in the same manner as described above.

The heat resistance cycle number of the surface observation result of the electrode film 21 when the addition amount of manganese is 1% by weight, 4% by weight, or 9% by weight will be described using FIG. 9. In addition, the illustration of the SEM image of the electrode film 21 when the addition amount of manganese is 1 wt% and 4 wt% is omitted.

9 is a graph showing the number of heat-resistant cycles with respect to the amount of metal (manganese) added to the electrode film in the second embodiment.

In FIG. 9 as well, the horizontal axis represents the added amount (wt%) of manganese, and the vertical axis represents the number of heat-resistant cycles (cycles) showing the number of cycles in which film degradation occurs. In addition, the circle symbol (◯) indicates the number of cycles of film degradation on the surface of the electrode film 21, and the solid line is a graph obtained from the circle symbol. The square symbol (□) indicates the number of cycles in which the film degradation of the crystal grain boundary of the electrode film 21 occurs, and the dotted line indicates the graph obtained from the square symbol. In addition, the film degradation of the grain boundary of the electrode film 21 when the addition amount of manganese was 9 wt% was not observed at 3000 cycles, but a square symbol with a broken line was drawn at a position corresponding to 3000 cycles in FIG. 9.

According to these two types of graphs, as the amount of manganese added increases, the number of heat-resistant cycles also increases. As illustrated in FIG. 8, it is conceivable that as the amount of manganese added to the electrode film 21 increases, the electrode film 21 becomes precipitation-hardened, the electrode film 21 becomes stronger, and the heat-resistant cycle characteristics are improved.

Also, compare with the number of heat-resistant cycles when nickel is added (Figure 6). For example, the number of heat-resistant cycles for the degradation of the film on the surface and grain boundaries is about 100 cycles and 500 cycles when the amount of nickel added is 5 wt%, respectively. When the amount of manganese added is 4wt%, it is about 1100 cycles and 1700 cycles. In addition, when the addition amount of nickel is 10 wt%, it is approximately 300 cycles and 500 cycles. On the contrary, when the addition amount of manganese is 9 wt%, it is approximately 1,000 cycles and 1700 cycles. In this way, it can be seen that when manganese is added, heat cycle resistance is improved more than when nickel is added.

In addition, from the range of the three types of addition amounts of manganese applied in the second embodiment, the addition amount of manganese is preferably at least 1 wt% or more. According to the graph of FIG. 7(C), the area ratio of the second phase particles in which the addition amount of manganese is 1 wt% or more is approximately 9% or more. Therefore, in order to improve the number of heat-resistant cycles of the electrode film 21, it is preferable that the area ratio of the second phase particles dispersed and deposited in the electrode film 21 be 9% or more.

In addition, as in the first embodiment, in order to obtain a heat-resistant cycle number equal to or higher than the heat-resistant cycle number (degree of 500 cycles) as in Patent Document 1, it can be seen from FIG. 9 that the addition amount of manganese to the electrode film 21 is 1.8 wt%. the above.

However, if the amount of manganese added to the electrode film 21 exceeds 40% by weight, the area ratio of the second phase particles of the electrode film 21 will increase. The risk of breaking the circuit of the semiconductor element 20 under load is increased. Therefore, it is preferable that the amount of manganese added is 1 wt% or more and 40 wt% or less.

The electrode film 21 of the semiconductor element 20 has aluminum as the main component and the second phase particles containing manganese added to aluminum are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more. As a result, precipitation hardening occurs in the electrode film 21, and the electrode film 21 becomes strong. The heat-resistant cycle characteristics of the pole film 21 are improved. Moreover, the second phase particles containing manganese are more resistant to nickel than nickel. In addition, it is preferable that the amount of manganese added to aluminum as the main component is 1 wt% or more and 40 wt% or less. Therefore, in the semiconductor element 20 having such an electrode film 21, the occurrence of stress migration of the electrode film 21 in a high-temperature environment is suppressed, reliability is improved, life is extended, and an increase in manufacturing cost can be suppressed.

The above merely shows the principle of the present invention, and many modifications and changes can be implemented for the practitioner. The present invention is not limited to the above-described configuration and application examples, and all corresponding modifications and equivalents are regarded as claims of the present invention and Within the range of their equivalents.

Claims (9)

A semiconductor element characterized by having an electrode film which contains aluminum as the main component, and contains the above-mentioned aluminum and 5 wt% or more of the aluminum added, the diffusion coefficient of 40 wt% or less is smaller than nickel, palladium and iron Or, the second phase particles of zirconium are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more. A semiconductor element characterized by having an electrode film which contains aluminum as a main component, and the second phase particles containing the aluminum and 1 wt% or more of the aluminum added and 40 wt% or less of manganese are dispersed and precipitated The area ratio of the second phase particles is 9% or more. For example, in the semiconductor device of claim 2, the aforementioned manganese is at least 1.8 wt%. A sputtering target characterized by using aluminum as a main component for forming an electrode film on a semiconductor element as described in item 1 of the patent application scope by a sputtering method. For example, the sputtering target material in the fourth item of the patent application scope, which contains 0.1 wt% or more and 5 wt% or less of silicon, and contains 5 wt% or more and 40 wt% or less of any one of palladium, iron and zirconium as the aforementioned added metal . A sputtering target characterized by using aluminum as a main component for forming an electrode film on a semiconductor element as described in item 2 or 3 of the patent application scope by a sputtering method. For example, the sputtering target in the 6th scope of the patent application contains more than 0.1wt% and less than 5wt% silicon. A semiconductor device characterized by comprising: an insulating substrate; and a semiconductor element, which is arranged on the insulating substrate, has an electrode film, the electrode film is composed of aluminum as a main component, and contains the aluminum and the aluminum added to the aluminum The second phase particles of palladium, iron, or zirconium with a diffusion coefficient of 5 wt% or more and a diffusion coefficient of 40 wt% or less than nickel are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more. A semiconductor device characterized by comprising: an insulating substrate; and a semiconductor element, which is arranged on the insulating substrate, has an electrode film, the electrode film is composed of aluminum as a main component, and contains the aluminum and the aluminum added to the aluminum The second phase particles of manganese of 1 wt% or more and 40 wt% or less are dispersed and precipitated, and the area ratio of the second phase particles is 9% or more.