JP2006253437A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device manufacturing method which is capable of preventing the residual glue layer of a protective tape, protects the surface of a semiconductor substrate when the rear of the semiconductor substrate is subjected to processing from being left on the surface of a projecting electrode, hardly causes cracking to a semiconductor board, and is excellent in workability. <P>SOLUTION: The semiconductor device manufacturing method contains a process of removing the glue layer residues 36 of the protective tape 34, which occurs after the rear of the semiconductor substrate is subjected to a treatment through a dry treatment without using a wet treatment in which the glue layer residues are dipped into the a resist solvent or a rinse solution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly, a manufacturing method in which a protective tape is attached to the surface of a semiconductor substrate, processed from the back surface of the semiconductor substrate to reduce the thickness after forming the protruding electrodes, and then the protective tape is peeled off. The present invention relates to a method for manufacturing a semiconductor device free from adhesive layer residue of a protective tape.

Conventionally, the performance of a semiconductor device has been dominant as an element that determines the product value of a semiconductor device.
In recent years, due to improvements in mounting technology, mounting structures corresponding to semiconductor device applications have been demanded, and flip chip technology that can achieve high-density mounting in the mounting structures has attracted attention. Further, if the thickness of the semiconductor substrate can be reduced, a very thin mounting structure can be realized, and a three-dimensional mounting in which thin semiconductor chips are stacked provides a mounting structure with further improved integration. Is possible.
Therefore, not only semiconductor device performance but also mounting technology and technology for reducing the thickness of the semiconductor substrate have become important elemental technologies.

Conventionally, when reducing the thickness of a semiconductor substrate, a protective tape for protecting the surface of the semiconductor substrate is attached to the surface of the semiconductor substrate to process the back surface of the semiconductor substrate. This protective tape is composed of a glue layer as an adhesive layer and a base material that holds the glue layer.
However, this method has a problem in that the adhesive layer of the protective tape remains on the surface of the insulating film and the protruding electrode of the semiconductor substrate to generate an adhesive layer residue.

Thus, for example, Patent Document 1 discloses a manufacturing method in which the adhesive layer residue is not generated. In the manufacturing method described in Patent Document 1, after a photoresist is formed on the surface of the semiconductor substrate so as to cover the top of the protruding electrode, a protective tape is applied on the photoresist to grind the back surface of the semiconductor substrate. A process of reducing the thickness of the semiconductor substrate and then peeling off the protective tape is employed. The protective tape has a role of protecting the surface of the semiconductor substrate on the protruding electrode forming surface side when grinding the back surface of the semiconductor substrate.
JP 2002-261060 (paragraphs 0014 to 0015 and FIG. 2)

  In the manufacturing method described in Patent Document 1 described above, the protruding electrode is completely covered with a photoresist and a protective tape is pasted on the photoresist, and the residue of the adhesive layer of the protective tape remains on the surface of the protruding electrode. Has the advantage of not.

In the conventional manufacturing method, after the semiconductor substrate back surface processing, the protective tape is peeled off by a lift-off method in which the semiconductor substrate is immersed in a photoresist solvent to dissolve the photoresist and peel off the protective tape on the photoresist. . Furthermore, after the photoresist and the protective tape are lifted off with the photoresist solvent, it is necessary to perform a rinsing process to remove the photoresist solvent from the surface of the semiconductor substrate. That is, in the prior art, it is necessary to perform wet processing twice.
In this wet stripping process and rinsing process, a thin semiconductor substrate is immersed in a photoresist solvent or a rinsing liquid, so that stress is applied to the semiconductor substrate, causing cracks, and the semiconductor substrate becomes defective. . In particular, cracks frequently occur in a semiconductor substrate having a thickness as thin as 100 to 200 μm or a semiconductor substrate having a large diameter, and the manufacturing yield is extremely deteriorated.
The backside processing of the semiconductor substrate is the final stage of the manufacturing process of the semiconductor device. After the backside processing, dicing is performed and the process of mounting the semiconductor chip in the shape of a chip on the circuit board is left. It is necessary to reduce the damage of the semiconductor substrate in the process as much as possible.

Further, in Patent Document 1 described above, in order to prevent the residue of the adhesive layer of the protective tape from adhering to the surface of the protruding electrode, it is necessary to form a photoresist with a thickness that completely covers the protruding electrode. That is, if the height of the protruding electrode is 100 μm, the photoresist must be formed with a thickness of 100 μm or more.
The photoresist is formed by a spin coating method. However, in order to form a thick photoresist, it cannot be formed by a single spin coating. If the photoresist has a thickness of 100 μm, it is necessary to perform spin coating a plurality of times, resulting in poor workability.

  The present invention solves the above problems, there is no adhesive layer residue of the protective tape that protects the surface of the semiconductor substrate when processing the back surface of the semiconductor substrate on the surface of the protruding electrode, and further without cracking of the semiconductor substrate, In addition, an object is to provide a method for manufacturing a semiconductor device with good workability.

In order to achieve the above object, the method described below is employed in the method of manufacturing a semiconductor device according to the present invention.
Forming a protruding electrode on the electrode pad of the semiconductor substrate; protecting the semiconductor substrate surface and the protruding electrode; attaching a protective tape having a glue layer to the semiconductor substrate surface; and processing the back surface of the semiconductor substrate to form the semiconductor substrate In the manufacturing method of a semiconductor device having a step of reducing the thickness of the semiconductor device and a protective tape peeling step of peeling the protective tape from the surface of the semiconductor substrate, a dry process is performed after the protective tape peeling step to remove the adhesive layer residue of the protective tape It is characterized by that.

In the prior art, a photoresist is formed so as to cover the protruding electrodes, a protective tape is attached on the photoresist, and the protective tape is peeled off by a wet process.
On the other hand, in the present invention, a protective tape is applied directly on the protruding electrode, the back surface of the semiconductor substrate is processed, and after the protective tape is peeled off, the adhesive layer residue of the protective tape remaining on the protruding electrode surface is removed by dry processing. Yes. In the present invention, instead of the conventional wet process of immersing the semiconductor substrate in a resist solvent or a rinsing liquid, the adhesive layer residue of the protective tape is removed by a dry process. In dry processing, a semiconductor substrate is placed in a reaction chamber, and a gas capable of reacting with the glue layer and removing a residue is introduced into the reaction chamber. For this reason, in the manufacturing method of the present invention, it is possible to completely remove the glue layer, there is no glue layer residue, no cracking of the semiconductor substrate occurs, and the production yield is high.

As the dry process, it is particularly preferable to perform an ashing process that hardly damages the semiconductor device. In the ashing treatment, oxygen in the plasma atmosphere reacts with the paste layer residue, changes to carbon dioxide and water, and is ashed (ashed) to completely remove the paste layer residue.
Further, in the present invention, since the protective tape is directly attached on the protruding electrode, there is no step of forming a photoresist with a film thickness that covers the protruding electrode by a plurality of spin coating methods as in the prior art, and the workability is It is good.
Furthermore, in the prior art, the waste liquid of the photoresist solvent and the rinsing liquid may adversely affect the environment. However, in the manufacturing method of the present invention, the paste layer is formed by a dry process that does not use the photoresist solvent or the rinsing liquid as in the prior art. No environmental pollution occurs because the residue is removed.

Hereinafter, a semiconductor device manufacturing method in the best mode for carrying out the present invention will be described in detail with reference to the drawings.
In the following description, the surface of the semiconductor substrate is the surface side where the protruding electrodes are formed, and the back surface of the semiconductor substrate is the surface side where the protruding electrodes are not formed.

  1 to 5 are cross-sectional views showing a method of manufacturing a semiconductor device according to the first embodiment of the present invention. The first embodiment of the present invention will be described with reference to the drawings.

First, as shown in FIG. 1, an opening is formed in the insulating film 16 so that the electrode pad 14 on the semiconductor substrate 12 is exposed.
Thereafter, a first barrier metal 24 is formed on the entire surface of the semiconductor substrate 12.

  The first barrier metal 24 is sequentially formed from the semiconductor substrate 12 side by a sputtering method with a titanium / tungsten alloy having a thickness of 0.1 to 0.5 μm and a copper having a thickness of 0.2 to 1 μm. The first barrier metal 24 has a multilayer structure, has a role of a connection layer with the electrode pad 14 and a role of a barrier layer to prevent mutual diffusion, and also has a role as an electrode when the protruding electrode is formed by a plating method. .

Next, a photoresist is formed on the entire surface by spin coating, and the photoresist in the protruding electrode formation region is opened by a photolithographic process such as an exposure process and a development process using a predetermined photomask.
Thereafter, copper is formed as the second barrier metal 22 on the first barrier metal 24 in the photoresist opening by a plating method. At this time, the first barrier metal 24 is used as an electrode for plating.
The second barrier metal 22 serves to prevent mutual diffusion between the protruding electrode 10 made of solder and the first barrier metal 24, and a copper plating layer is formed with a thickness of 5 to 25 μm. As the second barrier metal 22, nickel or a nickel alloy can be applied in addition to copper.

Thereafter, solder is formed as the protruding electrode 10 on the second barrier metal 22 in the opening of the photoresist by a plating method using the first barrier metal 24 as a plating electrode. The protruding electrode 10 may be formed by using a method of mounting a solder ball in the photoresist opening or a method of filling a solder paste in the photoresist opening with a squeegee in addition to forming the solder using a plating method. .
Thereafter, the photoresist is peeled off, and the first barrier metal 24 exposed from the protruding electrode 10 is removed by etching.

  Next, a flux is formed on the entire surface of the semiconductor substrate 12 by a spin coating method to a thickness of 10 to 50 μm, and a reflow process (wetback process) is performed at a temperature of 230 to 260 ° C. The solder is melted by the reflow process, and the spherical protruding electrode 10 is obtained.

The bump electrode 10 is formed to a height of about 100 μm by this wet back treatment.
Thereafter, a cleaning process is performed to remove the flux.

  Next, as shown in FIG. 2, the protective tape 34 is uniformly applied to the entire surface of the semiconductor substrate 12 by controlling the sticking pressure to a pressure of 0.2 to 0.3 MPa and the sticking speed to a speed of 10 to 20 mm / sec. Paste.

The protective tape 34 includes a base material 30 and a glue layer 32 that is an adhesive layer. The thickness of the base material 30 is 100 to 200 μm, and the thickness of the glue layer 32 is 100 to 150 μm.
The protective tape 34 absorbs the height difference of 100 μm of the protruding electrode 10 to smooth the surface of the base material 30, and protects the protruding electrode 10 forming surface side at the same time when grinding the back surface of the semiconductor substrate 12. By absorbing the height of 10, the semiconductor substrate 12 is prevented from cracking due to stress during the back grinding process.

  Thereafter, as shown in FIG. 3, the semiconductor substrate 12 is subjected to back grinding to a thickness of 100 to 200 μm by rough grinding and finish grinding using a back grinding apparatus.

Next, as shown in FIG. 4, the protective tape 34 is irradiated with ultraviolet rays of 500 to 1000 mj / cm ² . The adhesive layer 32 is cured and the adhesive strength is reduced by the ultraviolet irradiation, and the protective tape 34 is easily peeled from the surface of the semiconductor substrate 12.

  As the protective tape 34, an ultraviolet non-irradiation type tape can be used in addition to the ultraviolet curable tape. In the case of this ultraviolet non-irradiated type tape, the protective tape can be peeled off immediately after grinding the back surface of the semiconductor substrate 12 without performing ultraviolet irradiation.

  Also in this ultraviolet non-irradiated type tape, the adhesive layer 32 is left on the surface on the protruding electrode 10 and the insulating film 16 by peeling from the base material 30 and the adhesive layer residue 36 is generated.

The reason for the generation of the adhesive layer residue 36 is that a minute air layer is formed by the unevenness of the protruding electrode 10 and the insulating film 16 in the attaching process of the protective tape 34, and the adhesive layer 32 is sufficiently cured by the ultraviolet irradiation. Therefore, it is considered that the paste layer 32 remains on the surface of the protruding electrode 10 and the insulating film 16 so that the paste layer 32 is transferred.
Moreover, in the above-mentioned ultraviolet non-irradiation type tape, since the glue layer 32 is not cured, transfer of the glue layer 32 occurs as in the case of the ultraviolet curable tape.

  When the protruding electrode 10 is mounted on the circuit board without removing the adhesive layer residue 36, the adhesive layer residue 36, which is an insulator, remains on the bonding interface, and the bonding failure between the protruding electrode 10 and the circuit board or the connection resistance value is reduced. Bonding failure due to an increase or a change with time is caused, and the mounting reliability is lowered. For this reason, it is necessary to completely remove the adhesive layer residue 36.

Thereafter, as shown in FIG. 5, the semiconductor substrate 12 is placed in a reaction chamber for dry processing. As a dry process, oxygen gas is introduced as a reaction gas at a flow rate of 200 to 300 sccm and a high frequency power is supplied at an output of 1 KW to 1.5 KW in an oxygen plasma atmosphere in a vacuum chamber which is a reaction chamber of a high frequency oxygen plasma generator. A semiconductor substrate 12 is disposed therein.
In the reaction chamber, the glue layer residue 36 reacts with oxygen in oxygen plasma to change to carbon dioxide and water, and the glue layer residue 36 is ashed (ashed) and can be removed.

  As the reactive gas, a gas such as nitrogen, hydrogen, carbon tetrachloride, sulfur hexafluoride or the like is added to the oxygen gas to increase the reaction rate and enable a short-time treatment.

  As described above, by performing the ashing process which is a dry process in an oxygen plasma atmosphere, it is possible to completely remove the adhesive layer residue 36 attached to the surface of the insulating film 16 and the surface of the protruding electrode 10.

In the manufacturing method according to the present invention, since the dry processing is used to remove the adhesive layer residue 36, the semiconductor substrate 12 which has been back-ground to a thickness of 100 to 200 μm is subjected to a resist solvent and a rinsing process for wet resist stripping as in the prior art. It is not immersed in the rinse liquid. For this reason, as in the prior art, stress is applied to the semiconductor substrate 12 to cause cracks, so that a semiconductor device can be manufactured with a high yield without causing defects.

  Further, by removing the adhesive layer residue 36 by dry processing, the resist solvent and the rinsing liquid used in the peeling and cleaning steps are not used. Therefore, the waste liquid does not adversely affect the environment, and the adhesive layer residue 36 can be removed cleanly.

  As described above, in the manufacturing method according to the present invention, there is no occurrence of defective cracking of the semiconductor substrate 12, and the adhesive layer residue 36 is completely removed, thereby providing a highly reliable semiconductor device. In addition, it is possible to provide a manufacturing method that is very effective in industrial production.

  Next, a second embodiment of the present invention will be described with reference to the drawings. 6 to 10 are sectional views showing a method of manufacturing a semiconductor device according to the second embodiment of the present invention.

First, as shown in FIG. 6, an opening is formed in the insulating film 16 so that the electrode pad 14 made of aluminum on the semiconductor substrate 12 is exposed.
Thereafter, a barrier metal 23 is formed on the entire surface of the semiconductor substrate 12.

  The barrier metal 23 is sequentially formed from the semiconductor substrate 12 side by a sputtering method with a titanium / tungsten alloy having a thickness of 0.1 to 0.5 μm and gold (Au) having a thickness of 0.05 to 0.2 μm. The barrier metal 23 has a multi-layer structure, a role of a connection layer between the electrode pad 14 and the protruding electrode, a role of a barrier layer for preventing mutual diffusion, and a role as a plating electrode when the protruding electrode is formed by a plating method. Have.

Thereafter, a photoresist is formed on the entire surface of the barrier metal 23 by a spin coating method, and the photoresist is patterned by a photolithography technique so that the protruding electrode formation region is opened.
Thereafter, the bump electrode 11 made of gold (Au) is formed in a height of 10 to 50 μm in the photoresist opening by the plating method using the barrier metal 23 as an electrode. When the gold plating thickness is the same as the photoresist thickness or thinner than the photoresist thickness, the side walls of the protruding electrodes 11 become a straight shape as shown in FIG. 6, and the pitch dimension between the protruding electrodes 11 can be miniaturized. The top of the protruding electrode 11 has a cross-sectional shape with a recessed central portion as compared with the peripheral portion, reflecting the step caused by the electrode pad 14 and the insulating film 16 below the protruding electrode 11.
The material of the protruding electrode 11 may be gold alloy, platinum, platinum alloy, nickel, copper, or solder other than gold.
Thereafter, the photoresist is peeled off, and the barrier metal 23 exposed from the protruding electrode 11 is removed by etching.

  Next, as shown in FIG. 7, the protective tape 34 is applied to the entire surface of the semiconductor substrate 12 so that the pressure is 0.2 to 0.3 MPa and the application speed is 10 to 20 mm / sec.

  The protective tape 34 includes a base material 30 and an adhesive layer 32 as an adhesive layer. The base material 30 has a thickness of 100 to 200 μm, and the adhesive layer 32 has a thickness of 100 to 150 μm. When the paste layer 32 absorbs the height of the protruding electrode 11 having a thickness of 10 to 50 μm, the surface of the base material 30 is smoothed, and when the back surface of the semiconductor substrate is ground, the protruding electrode forming surface side is protected and at the same time By absorbing the thickness, the semiconductor substrate 12 is prevented from being damaged by the stress applied during the back grinding process.

Thereafter, as shown in FIG. 8, rough grinding is performed using a back grinding apparatus, and then the semiconductor substrate 12 is ground from the back to a thickness of 100 to 200 μm through a finishing grinding process.

Next, as shown in FIG. 9, the protective tape 34 is irradiated with ultraviolet rays of 500 to 1000 mj / cm ² . The adhesive layer 32 is cured and the adhesive strength is reduced by the ultraviolet irradiation, and the protective tape 34 can be easily peeled off from the semiconductor substrate 12.

  As the protective tape 34, an ultraviolet non-irradiation type tape can be used in addition to the ultraviolet curable tape. In the case of this ultraviolet non-irradiated type tape, the protective tape can be peeled off immediately after grinding the back surface of the semiconductor substrate 12 without performing ultraviolet irradiation.

  Even when the protective tape 34 is a non-ultraviolet irradiation type tape, the adhesive layer 32 is transferred to the surface on the protruding electrode 11 and the insulating film 16 to generate an adhesive layer residue 36.

The adhesive layer residue 36 forms a fine air layer due to irregularities on the surface of the protruding electrode 11 and the surface of the insulating film 16 when the protective tape 34 is applied, and the adhesive layer 32 is not sufficiently cured by ultraviolet irradiation. Therefore, it is considered that the adhesive layer 32 remains so as to be transferred.
Further, in the case where the above-mentioned protective tape 34 is an ultraviolet non-irradiated type tape, the adhesive layer is not cured, so that the adhesive layer 32 is transferred to the protruding electrodes 11 and the insulating film 16 as in the case of the ultraviolet curable tape.

When the protruding electrode 11 is mounted on the circuit board with the adhesive layer residue 36 remaining, the adhesive layer residue 36 that is an insulator transferred onto the surface of the protruding electrode 11 remains at the bonding interface, and the protruding electrode 11 and the circuit board are A bonding failure and an increase in connection resistance value and a bonding failure due to a change with time occur, and the mounting reliability is lowered.
Therefore, it is necessary to completely remove the adhesive layer residue 36.

Then, as shown in FIG. 10, the semiconductor substrate 12 is mounted in the reaction chamber of the dry process. In dry processing, oxygen gas is introduced as a reaction gas at a flow rate of 200 to 300 sccm, and high frequency power is supplied at an output of 1 to 1.5 kW to generate oxygen plasma in a vacuum chamber which is a reaction chamber of a high frequency oxygen plasma generator. The semiconductor substrate 12 is placed in the atmosphere.
In the reaction chamber where the oxygen plasma is generated, the glue layer residue 36 reacts with oxygen, changes to carbon dioxide and water, and is ashed (ashed) to remove the glue layer residue 36.

  In addition, as reactive gas, nitrogen, hydrogen, carbon tetrachloride, sulfur hexafluoride, and other gases can be added to oxygen gas to increase the reaction rate and shorten the dry processing time. is there.

  As described above, by performing the ashing process which is a dry process in an oxygen plasma atmosphere, it is possible to completely remove the adhesive layer residue 36 attached to the surface of the insulating film 16 and the surface of the protruding electrode 11.

  In the manufacturing method according to the present invention, since the dry processing is used to remove the glue layer residue 36, the semiconductor substrate 12 whose back surface is ground to a thickness of 100 to 200 μm is subjected to a wet-processed photoresist solvent and a rinsing process as in the prior art. There is no immersion in the rinse liquid. As a result, stress is applied to the semiconductor substrate 12 as in the conventional case, cracking occurs, and no semiconductor device can be manufactured with high yield without causing defects.

In addition, by removing the adhesive layer residue 36 by dry processing, the photoresist solvent and rinse liquid used in the peeling process and the cleaning process are not used, so that the waste liquid does not adversely affect the environment and clean cleaning and removal are performed. I can do it.

  As described above, according to the present invention, by performing the ashing process after the back surface grinding process, there is no occurrence of cracking failure of the semiconductor substrate 12, the adhesive layer residue 36 can be completely removed, and the mounting reliability of the protruding electrode 11 and the circuit board can be reduced. A highly reliable semiconductor device can be provided, and a semiconductor device manufacturing method useful for industrial production can be provided.

It is sectional drawing which shows the manufacturing method of the semiconductor device in 1st Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 1st Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 1st Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 1st Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 1st Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 2nd Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 2nd Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 2nd Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 2nd Example of this invention. It is sectional drawing which shows the manufacturing method of the semiconductor device in 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Projection electrode 11 Projection electrode 12 Semiconductor substrate 14 Electrode pad
16 Insulating Film 22 Second Barrier Metal 23 Barrier Metal 24 First Barrier Metal 30 Base Material 32 Adhesive Layer 34 Protective Tape 36 Adhesive Layer Residue

Claims (3)

Forming a protruding electrode on an electrode pad of a semiconductor substrate, applying a protective tape having a paste layer to protect the surface of the semiconductor substrate and the protruding electrode, and processing the back surface of the semiconductor substrate In the method of manufacturing a semiconductor device, the method includes reducing the thickness of the semiconductor substrate, and the protective tape peeling step of peeling the protective tape from the surface of the semiconductor substrate.
A dry process is performed after the protective tape peeling step to remove the adhesive layer residue of the protective tape. The method for manufacturing a semiconductor device according to claim 1, wherein the dry process is a plasma process. The method of manufacturing a semiconductor device according to claim 2, wherein the plasma treatment is an ashing treatment.

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