JP2011138858A - Manufacturing method for thin semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a thin semiconductor device that achieves reuse of a substrate material and a significant reduction in machining time for thinning, moreover, preventing a thinned semiconductor device from breaking. <P>SOLUTION: The manufacturing method is used for manufacturing a thin semiconductor device in which a circuit element is formed on a semiconductor substrate, and the method has a separation step for separating an unnecessary part of the semiconductor substrate from the semiconductor substrate along the horizontal plane at a prescribed depth of the semiconductor substrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a thin semiconductor device that can significantly reduce the time required for reuse and thinning of a substrate material, and that can break down a thinned semiconductor device.

As information terminal devices are rapidly becoming thinner, smaller, and multifunctional, semiconductor devices mounted on them are also required to be thinner and denser. Recently, a completed semiconductor device is often thinly ground to a thickness of 50 μm or less and separated into chips.
However, considering that the thickness of the semiconductor device before grinding is 700 μm or more, in the above method, most of the substrate material of the semiconductor device is discarded in the thin grinding process, and from the viewpoint of cost, processing time, and environment. It is not efficient. Further, since the semiconductor device after thin grinding is fragile and very weak against external impacts, the thinned semiconductor device may be destroyed in the subsequent processes. In particular, with the increase in diameter of semiconductor devices, the vulnerability of thin semiconductor devices has become a serious problem.

  In connection with the present invention, in the manufacture of an SOI (Silicon on Insulator) substrate, hydrogen atoms are introduced to a semiconductor substrate at a high concentration to a depth of several microns by an ion implantation method, and further subjected to heat treatment and / or external impact. Thus, techniques for peeling the semiconductor substrate along the hydrogen ion implantation interface of the semiconductor substrate are known (Patent Documents 1 to 4).

US2002 / 0023725A1 US2002 / 0115264A1 JP 2007-250576 A JP 2008-263010 A

  The present invention has been made in view of the above-described circumstances, and can recycle the substrate material and greatly reduce the processing time for thinning, and can solve the problem that the thinned semiconductor device is destroyed. It is an object of the present invention to provide a method for manufacturing a thin semiconductor device.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have formed a separation layer in advance in the substrate instead of a method of thinly grinding the back surface of the semiconductor substrate after forming the circuit pattern in the manufacturing method of the thin semiconductor device. A surface protection sheet is affixed to the circuit surface of the semiconductor substrate, the circuit surface is protected and the substrate is fixed, and the semiconductor substrate is separated along the separation layer interface by applying an impact. We found that it can be manufactured well. According to this method, since the substrate with the surface protective sheet attached can be diced as it is, the semiconductor substrate can be prevented from being damaged in the subsequent process, and the peeled substrate can be removed from the semiconductor device. As a result, the present invention has been completed.

Thus, according to the present invention, the method for manufacturing a thin semiconductor device of (1) to (9) is provided.
(1) A method for manufacturing a thin semiconductor device in which circuit elements are formed on a semiconductor substrate, wherein an unnecessary portion of the semiconductor substrate is separated from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. A method for manufacturing a thin semiconductor device.
(2) The method for manufacturing a thin semiconductor device according to (1), wherein the separation step is performed after circuit elements are formed on a semiconductor substrate.
(3) The semiconductor substrate before the separation step has at least one separation layer serving as an interface for separating unnecessary portions of the semiconductor substrate from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. A method for manufacturing a thin semiconductor device according to (1) or (2).

(4) The method for manufacturing a thin semiconductor device according to (3), wherein the separation layer is made of at least one material different from a semiconductor substrate material.
(5) The method for manufacturing a thin semiconductor device according to (3) or (4), wherein the separation layer is formed by an ion implantation method.
(6) The method for manufacturing a thin semiconductor device according to any one of (1) to (5), wherein the semiconductor device is separated in a state of being fixed to an adhesive sheet.

(7) The method for manufacturing a thin semiconductor device according to any one of (1) to (6), including a step of separating the semiconductor device into chips after the separation step.
(8) The method for manufacturing a thin semiconductor device according to (7), including a step of dividing the semiconductor device into chips in a state of being fixed to the adhesive sheet.
(9) The method for manufacturing a thin semiconductor device according to any one of (1) to (8), wherein an unnecessary portion of the separated semiconductor substrate is reused as a material for manufacturing a semiconductor device.

  According to the present invention, even when a thin semiconductor substrate or a large-diameter semiconductor substrate is processed, damage to the substrate can be reduced, and the separation substrate generated when the semiconductor substrate is thinned can be removed again from the semiconductor. A method of manufacturing a thin semiconductor device that can be used as a substrate is provided.

7 is a manufacturing process cross-sectional view of the thin semiconductor device of Example 1. FIG. 7 is a manufacturing process cross-sectional view of the thin semiconductor device of Example 1. FIG. 7 is a manufacturing process cross-sectional view of the thin semiconductor device of Example 2. FIG. 7 is a manufacturing process cross-sectional view of the thin semiconductor device of Example 2. FIG.

Hereinafter, the manufacturing method of the thin semiconductor device of this invention is demonstrated in detail.
A thin semiconductor device has a semiconductor substrate and a circuit element formed on the semiconductor substrate. The thickness is usually in the range of 0.5 μm to 200 μm.
The present invention relates to a method of manufacturing such a thin semiconductor device.

  The semiconductor substrate used for the manufacturing method of the present invention is not particularly limited. For example, a single crystal silicon substrate, a single crystal SiC substrate, a single crystal GaAs substrate, etc. are mentioned, and a single crystal silicon substrate is preferable. The single crystal silicon substrate may be an untreated silicon substrate or an oxidized silicon substrate. Further, it may be a substrate having an SOI (Silicon on Insulator) structure.

  The manufacturing method of the present invention includes a separation step of separating an unnecessary portion of the semiconductor substrate from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate.

  In the present invention, from the viewpoint of work efficiency, it is preferable to perform the separation step after forming circuit elements on the semiconductor substrate.

  In the present invention, the semiconductor substrate before the separation step has at least one separation layer serving as an interface that separates unnecessary portions of the semiconductor substrate from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. Is preferred. Here, the “unnecessary part of the semiconductor substrate” refers to a part of the surface of the semiconductor substrate where the circuit elements are not formed and separated (separated) in order to reduce the thickness of the semiconductor device.

  The separation layer may be formed before or after the circuit element is formed on the semiconductor substrate. From the viewpoint of reducing damage to the circuit element, the separation layer is formed from a circuit. It is preferable to form the device before forming the device.

  The material constituting the separation layer may be different from the substrate material, but a material having a thermal expansion coefficient different from that of the substrate material is preferable. Further, a material that increases kinetic energy when heat is applied, that is, a material having a relatively small mass number may be used.

Examples of the method for forming the separation layer include an ion implantation method and a thermal diffusion method.
As an ion implantation method, (i) Paul K. et al. Chu, Chung Chan, Nathan W. Cheung, name “Recent Applications of Plasma Immersion Ion Implantation”, SEMICONDUCTOR INTERNATIONAL, pages 165-172, June 1996, (ii) P.A. K. Chu, S .; Qin, C.I. Chan, N.A. W. Cheung, L.C. A. Larson, name “Plasma Immersion Ion Implantation”, (iii) MATERIAL SCIENCE AND ENGINEERING REPORTS, A Review Journal, pp. 207-280, Vol. 6-7 (November 30, 1996) etc. Plasma ion implantation ("PIII") method; Method using ion shower; Hydrogen ion beam (Atomic energy eye, Vol. 46 (9) (2000) p61 -65); a plasma ion implantation method (Japanese Patent Laid-Open No. 2006-70238, etc.); and the like.
Any of these methods is preferable in that a desired material can be introduced into a target depth by ionizing a desired material, accelerating it with an external electric field, and injecting the material into a semiconductor substrate.

  The thermal diffusion method is a method of forming a separation layer by forming a desired material on the surface of a semiconductor substrate in advance and then diffusing the desired material into the substrate by heating the substrate. For example, a diffusion source having a thermal diffusion coefficient different from that of a semiconductor substrate dissolved in an organic solvent is applied to the surface of the semiconductor substrate by a spin coating method or the like. Thereafter, a semiconductor substrate coated with a diffusion source is put into an electric furnace at about 1000 ° C., whereby a material having a thermal expansion coefficient different from that of the semiconductor substrate can be formed in the semiconductor device by a thermal diffusion method. According to the thermal diffusion method, an expensive ion implantation apparatus is not required, which is preferable in terms of cost. Alternatively, a desired material may be introduced into the substrate by a thermal diffusion method after a desired material is introduced into the extreme surface of the semiconductor substrate by ion implantation.

  Among these, the ion implantation method is preferable because a predetermined amount of ions can be easily introduced into a predetermined position (depth) of the semiconductor substrate.

  The ion implanted by the ion implantation method is not particularly limited as long as it is an ion, but easily penetrates to a selected depth through the substrate material without substantially damaging the material region traversed by the particle. In view of the possibility, a material having a small mass is preferable. For example, from the viewpoint of gas barrier properties and transparency, at least one ion selected from the group consisting of hydrogen, oxygen, nitrogen, argon, helium, neon, krypton, and xenon is preferable, and ions of nitrogen, oxygen, argon, or helium are preferable. Particularly preferred.

The dose during ion implantation is usually 1 × 10 ¹⁵ to 1 × 10 ¹⁸ atoms / cm ² , preferably 1 × 10 ¹⁶ to 1 × 10 ¹⁸ atoms / cm ² .
The implantation energy is usually 1 keV to 1 MeV, preferably 10 to 200 keV.

  The depth of the separation layer from the substrate surface (ion implantation depth L) can be controlled by the acceleration voltage at the time of ion implantation, and is determined depending on the thickness of the semiconductor device to be separated. Can do. For example, the ion implantation depth (depth from the substrate surface) L can be 0.5 μm to 200 μm, the voltage 50 to 100 keV, and the like.

  In addition, in order to suppress channeling of implanted ions in the ion implantation process into the semiconductor substrate, an insulating film such as an oxide film is formed in advance on the ion implantation surface of the semiconductor substrate, as is normally done, and this insulation is performed. Ion implantation may be performed through the film.

  The unnecessary portion of the semiconductor substrate can be separated from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. When the separation layer is formed on the semiconductor substrate, after the separation layer is formed, an unnecessary portion of the semiconductor substrate can be separated using the separation layer as an interface by mechanical or thermal stress.

Examples of the separation method include methods described in Patent Documents 1 to 4 and the like.
More specifically, using a spray nozzle, while spraying a compressed fluid to the portion where the separation layer is formed on the side surface of the semiconductor substrate, mechanically the semiconductor substrate is peeled off as in a method of peeling off unnecessary portions of the semiconductor substrate. A method for separating an unnecessary portion from a separation layer; a method for separating an unnecessary portion of the semiconductor substrate from the separation layer by applying heat to the semiconductor substrate; The method of isolate | separating from a separated layer; etc. are mentioned. Among these, a method of mechanically separating an unnecessary portion of the semiconductor substrate from the separation layer and a method of separating the unnecessary portion of the semiconductor substrate from the separation layer by applying heat to the semiconductor substrate are preferable.

The method of mechanically separating the unnecessary portion of the semiconductor substrate from the separation layer does not require heating, and is suitable when using an adhesive sheet described later.
In the latter method of applying heat, the heating temperature is preferably in the range of 200 ° C. to 500 ° C., although it depends on the thermal expansion coefficient and mass number of the separation layer. When the temperature at the time of separation is higher than 500 ° C., the separation surface state after the separation becomes rough, and when it is lower than 200 ° C., the separation may be incomplete.

The thickness of the semiconductor substrate after separating unnecessary portions of the semiconductor substrate is usually in the range of 0.5 μm to 200 μm, preferably 1 μm to 100 μm, particularly preferably 2 μm to 50 μm. The thickness of the semiconductor substrate after separating unnecessary portions of the semiconductor substrate can be adjusted by the ion implantation depth L. If the thickness after separation of the semiconductor substrate is more than 200 μm, it takes time to form the separation layer, and if it is less than 0.5 μm, the semiconductor device becomes fragile and easily broken.
In addition, the thickness of the semiconductor substrate after separating unnecessary portions of the semiconductor substrate also depends on the thickness of the semiconductor substrate before separation. That is, the thickness of the semiconductor substrate to be separated is subtracted from the thickness of the semiconductor substrate before separation.

Since the semiconductor device after separating unnecessary portions of the semiconductor substrate is thin and fragile, it is extremely difficult to carry it alone. For this reason, it is desirable that the unnecessary portion of the semiconductor substrate is previously fixed to the adhesive sheet and then separated before separation.
According to this method, the dicing process can be performed as it is after the substrate on the back surface side is separated in the post process.

  The pressure-sensitive adhesive sheet to be used is not particularly limited, and conventionally known pressure-sensitive adhesive sheets can be used. However, since it is necessary to peel from the circuit surface in a later step, it is preferable to use a peelable pressure-sensitive adhesive sheet. Examples of such a pressure-sensitive adhesive sheet include a weak pressure-sensitive adhesive sheet and an energy ray-curable pressure-sensitive adhesive sheet that can reduce or eliminate the adhesive force by irradiation with energy rays.

In the present invention, an unnecessary portion of the semiconductor substrate may be separated after fixing the semiconductor device to the vacuum suction table in advance before separation, and then an adhesive sheet may be attached to the semiconductor device.
According to the process of fixing the semiconductor device to the vacuum suction table and separating it, the pressure-sensitive adhesive sheet is not used at the time of separation, so that separation by heating can be performed.

  The substrate remaining after the unnecessary portion of the semiconductor substrate is separated can be used again as a semiconductor device substrate. On the other hand, the separated semiconductor device has a separation surface mechanically polished, an etching process using plasma or a chemical solution, or a desired material such as a metal is formed by a physical vapor phase method or a chemical vapor phase method. May be.

The thin semiconductor device fixed to the adhesive sheet is separated into chips in a dicing process.
The method of singulation is not particularly limited, and examples thereof include a method of singulation using a normal blade, a method of singulation using a laser or ionizing radiation, and the like.

  In the present invention, before the unnecessary portion of the semiconductor substrate is separated, the circuit surface may be cut in advance with a blade, laser, or ionizing radiation and then separated from the separation layer. In this case, it is desirable that the depth of cut (thickness) is a thickness from the surface of the circuit element formation surface to a depth where the separation layer exists, or a thickness greater than that. In the method of cutting in the circuit surface in advance before the separation, the semiconductor device may be separated into chips at the same time as the separation, and may be scattered. It is preferable to separate it after sticking it to. This is because the thin semiconductor device separated into pieces after being separated is fixed to the adhesive sheet, so that the thin semiconductor device can be prevented from scattering.

  Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples.

(Example 1)
First, as shown in FIG. 1A, an 8-inch single crystal silicon substrate (1) having a thickness of 725 μm is used as a semiconductor substrate by using an ion implantation apparatus (manufactured by Rock Giken Co., Ltd.). Hydrogen ions are implanted from the element formation planned surface) so that the dose is 1 × 10 ¹⁶ to 1 × 10 ¹⁷ atoms / cm ² and the ion implantation depth L is 5 μm from the substrate surface, and the separation layer (2) is formed. Formed.
Next, after forming the circuit element (3) on the substrate surface, as shown in FIG. 1 (b), using a mounter device (RAD-2700F / 8, manufactured by Lintec Corporation) from the side surface of the semiconductor device to the circuit surface side. An adhesive sheet (Adwill D-678, manufactured by Lintec Corporation) (4a) was attached and fixed with a ring frame (5a).

  Thereafter, as shown in FIG. 1 (c), high compressed air is jetted onto the portion of the side surface of the substrate (1) where the separation layer (2) is formed using an jet nozzle. As shown in FIG. 2, the semiconductor device substrate was mechanically separated along the interface of the separation layer (2) to produce a thin semiconductor device (1a) fixed to the adhesive sheet. At this time, the separated semiconductor substrate (1b) can be reused as a substrate for a semiconductor device.

  Thereafter, as shown in FIG. 2 (e), IR (infrared ray) is applied from the back surface side of the thin semiconductor device (1a) obtained above using a dicing device (DFD 6340, manufactured by Disco Corporation) equipped with an IR camera. Then, dicing was performed while detecting the street line to obtain a thin semiconductor device (1a ′) separated into 1 mm × 1 mm chips.

(Example 2)
In the same manner as in Example 1, the production intermediate shown in FIG. Next, after the circuit element (3) was formed on the substrate surface, the circuit element (3) surface side of the semiconductor device was adsorbed and fixed to the vacuum adsorption table (6) as shown in FIG. 3 (f).
Next, as shown in FIGS. 3G and 3H, in the same manner as in Example 1, the semiconductor device was separated along the interface of the separation layer (2) to produce a thin semiconductor device (1a). . Next, as shown in FIG. 4 (i), a pressure-sensitive adhesive sheet (manufactured by Lintec, Adwill D-678) (4b) is attached to the separation surface of the semiconductor device (1a), and fixed with a ring frame (5b). The vacuum suction table (6) was detached.
Thereafter, as shown in FIG. 4 (j), from the surface side of the thin semiconductor device (1a), a dicing device (manufactured by Disco Corporation, DFD6340) is used to divide the chip into 1 mm × 1 mm chips, which are thin. The semiconductor device (1a ′) was obtained.

DESCRIPTION OF SYMBOLS 1 ... Single crystal silicon substrate (semiconductor substrate), 1a ... Semiconductor device, 1a '... Separated semiconductor device, 1b ... Separated semiconductor substrate, 2 ... Separation layer, 3. ..Circuit elements , 4a, 4b ... adhesive sheets, 5a, 5b ... ring frames, 6 ... vacuum suction tables

Claims (9)

  A method of manufacturing a thin semiconductor device in which circuit elements are formed on a semiconductor substrate, comprising a separation step of separating an unnecessary portion of the semiconductor substrate from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. A method for manufacturing a semiconductor device.   2. The method of manufacturing a thin semiconductor device according to claim 1, wherein the separation step is performed after forming a circuit element on a semiconductor substrate.   The semiconductor substrate before the separation step has at least one separation layer serving as an interface that separates an unnecessary portion of the semiconductor substrate from the semiconductor substrate along a horizontal plane of a predetermined depth of the semiconductor substrate. A method for manufacturing a thin semiconductor device according to claim 1.   4. The method of manufacturing a thin semiconductor device according to claim 3, wherein the separation layer is made of at least one material different from a semiconductor substrate material.   5. The method for manufacturing a thin semiconductor device according to claim 3, wherein the separation layer is formed by an ion implantation method.   The method of manufacturing a thin semiconductor device according to claim 1, wherein the semiconductor device is separated in a state of being fixed to an adhesive sheet.   The method for manufacturing a thin semiconductor device according to claim 1, further comprising a step of separating the semiconductor device into chips after the separation step.   The method for manufacturing a thin semiconductor device according to claim 7, further comprising a step of dividing the semiconductor device into chips in a state where the semiconductor device is fixed to the adhesive sheet.   The method for manufacturing a thin semiconductor device according to claim 1, wherein an unnecessary portion of the separated semiconductor substrate is reused as a material for manufacturing a semiconductor device.

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