JP2008034704A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device applicable to a miniature thin semiconductor device, particularly to a compound semiconductor device of GaAs or the like. <P>SOLUTION: After a circuit element is formed on a principal surface of a semiconductor substrate, a plurality of recesses 3 are formed in an electrode formation scheduled region. A metal film 4 connected with an electrode of the circuit element and covering an inner wall of the recess is formed and the inside of the recess is filled with an electrode metal 6. Thereafter, the surface is coated with a resin layer 7. The rear surface of the semiconductor substrate is etched to expose the metal film 4. Part of the electrode metal 6 filled in the recess is left behind in the recess, and the electrode metal is cut down into individual semiconductor devices. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device suitable for downsizing and thinning.

  In recent years, with the development of portable mobile communication and the like, various high-frequency devices such as a front end, a switch, and an amplifier are required, and GaAs semiconductor devices excellent in high-speed performance at high frequencies are often used.

  At the same time, this type of semiconductor device is strongly required to be small and thin. One of the technologies for realizing a small size and a thin thickness is a so-called wafer level CSP (chip scale package or chip size package). The wafer level CSP is formed, for example, by forming circuit elements on the main surface of the wafer, forming wiring layers and conductive posts, sealing the main surface with resin, forming bumps on the back surface, and then dividing into individual pieces. be able to. Recently, in order to further reduce the thickness of a semiconductor device, the back surface of a semiconductor wafer is also polished and removed.

Various methods for manufacturing a wafer level CSP in which a conductive post is not formed have been proposed. For example, in Patent Document 1, as a three-dimensional mounting package, a hole penetrating the chip pad on the main surface of the semiconductor substrate is formed, and after filling the electrode metal layer into this hole and polishing the back surface, the exposed electrode metal layer Discloses a technique for forming plated bumps. Furthermore, in Patent Document 2, a through hole is formed on a dicing line of a semiconductor substrate, the front and back surfaces of the wafer are electrically connected using the side surface, and an electrode for mounting the substrate is disposed on the back surface side to reduce the size. A technique for achieving this is disclosed. The through-hole is formed by half-etching the dicing line of the wafer to form a recess, and then polishing the back surface of the semiconductor substrate.
JP 2006-005343 A JP 2002-261192 A

  In the conventional wafer level CSP manufacturing method, the back surface of the semiconductor substrate is polished in order to reduce the size and thickness of the semiconductor device. In a thin semiconductor device mainly made of silicon, the thickness of the semiconductor substrate is polished to 50 to 100 μm, and even less. Such a thin semiconductor substrate is very easily broken. Therefore, the polishing technique has become sophisticated and special equipment is required. On the other hand, compound semiconductors such as GaAs are very fragile, and there is a limit to thinning by polishing according to a conventional manufacturing method made of silicon.

  An object of the present invention is to provide a method for manufacturing a semiconductor device that can be applied to a small and thin semiconductor device, particularly a compound semiconductor device such as GaAs, using only a normal semiconductor device manufacturing apparatus.

  In order to achieve the above object, an invention according to claim 1 of the present application includes a step of forming a circuit element on a main surface of a semiconductor substrate, and an electrode formation scheduled region along a dicing line adjacent to the element region where the circuit element is formed. Forming a plurality of recesses in the substrate, connecting the electrodes of the circuit elements, forming a metal film covering the inner wall of the recesses, filling the recesses with electrode metal, and then forming the main surface A step of coating with a resin layer; a step of etching another main surface of the semiconductor substrate to expose the metal film covering the inner wall of the recess; and the electrode filled in the recess along the dicing line A step of leaving a part of the metal on the side wall of the recess, cutting the resin layer, the semiconductor substrate, the electrode metal, and the metal film into individual semiconductor devices. To do.

  According to a second aspect of the present invention, in the method for manufacturing a semiconductor device according to the first aspect, the metal film is formed to cover the inner wall of the recess, and at the same time, the metal films are electrically connected to each other along the dicing line. Filling the inside of the recess with the electrode metal by selectively depositing an electrode metal in the recess by a charge supplied from the conductive line, and forming a conductive line to be connected; and the resin The conductive line is cut simultaneously with cutting the layer, the semiconductor substrate, the electrode metal and the metal film.

  According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first or second aspect, the step of dividing into the semiconductor device includes at least the metal film, the semiconductor substrate, and the electrode metal, or The method further comprises cutting the conductive line, cutting a part of the resin layer, and cutting the resin layer completely.

  In the manufacturing method of the present invention, the semiconductor substrate is thinned by etching without being polished, and further thinned after forming the resin layer on the main surface of the semiconductor substrate, so that the semiconductor substrate is not cracked. Furthermore, since the manufacturing method of the present invention includes only a normal semiconductor device manufacturing process, a semiconductor device can be formed with high yield.

  When a compound semiconductor device made of GaAs or the like is formed by the manufacturing method of the present invention, a compound semiconductor such as GaAs has better etching selectivity with respect to a metal than Si. Therefore, the semiconductor substrate can be thinned without damaging the metal constituting the electrode, which is preferable.

  Hereinafter, embodiments of the present invention will be described in detail by taking a method of manufacturing a semiconductor device made of compound semiconductor GaAs as an example.

  FIG. 1 is an explanatory diagram of a method of manufacturing a semiconductor device according to the first embodiment of the present invention. First, a plurality of circuit elements are formed on a semiconductor substrate 1 made of GaAs by an ordinary semiconductor device manufacturing method. In FIG. 1, one element region 2 in which circuit elements are formed is illustrated, and the circuit elements are not illustrated. Next, a plurality of recesses 3 are formed along dicing lines arranged between adjacent element regions 2 (FIG. 1a). The recess 3 is formed at a position where the electrode of the semiconductor device is formed.

  Next, a metal is vapor-deposited so that the inner wall of the recessed part 3 may be coat | covered by the normal photolithographic method, and the metal film 4 is patterned (FIG. 1b). Simultaneously with the patterning of the metal film 4, conductive lines 5 are formed along the dicing lines to electrically connect the metal films 3 to each other (FIG. 2). The electrode film 4 and the conductive line 5 may be either a single layer film or a multilayer film, and a metal having sufficient adhesion to the semiconductor substrate 1 and an electrode metal described later may be selected. As an example, gold (Au) can be used.

  Next, a voltage is applied to the conductive line 5, and the electrode metal 6 is filled in the recess 3 by electroplating. The electrode metal 6 is, for example, Au and is not shown. However, the photoresist is patterned so that a part of the metal film 4 is exposed, and the exposed metal film 4 is used using the photoresist as a mask. Selective plating is performed on the top (FIG. 1c). Note that the electrode metal 6 can also be formed in the recess 3 by electroless plating without forming the conductive line 5 in the above description.

  The entire main surface of the semiconductor substrate 1 on which the circuit elements and the electrode metal 6 are formed is covered with a resin layer 7 (FIG. 1d). The resin used here is, for example, an epoxy resin system, and is used by mixing a filler so that the semiconductor substrate 1 is not stressed. The resin layer 7 may be formed by any method such as potting, spin coating, or casting. Before the resin layer 7 is formed, it is preferable that the entire surface of the semiconductor substrate 1 is covered with a protective film such as SiN because reliability can be secured.

  Next, the semiconductor substrate 1 is thinned. In the present invention, the metal film 4 is exposed on the back surface (corresponding to another main surface) of the semiconductor substrate 1 using the etching solution of the semiconductor substrate 1 as shown in FIG. The semiconductor substrate 1 is etched until it protrudes to the back side. When the semiconductor substrate 1 is sufficiently thick, the semiconductor substrate 1 can be thinned by etching after the semiconductor substrate 1 is polished to a predetermined thickness. In this case, the semiconductor substrate 1 has a sufficient thickness, and since the resin layer 7 is formed on the main surface of the semiconductor substrate 1, no cracks or the like are generated by polishing. The dimension by which the metal film 4 or the like protrudes on the back side can be appropriately set by controlling the etching amount of the semiconductor substrate 1.

  Thereafter, a dicing saw is run along the dicing line from the back side of the semiconductor substrate 1 to cut a part of the metal film 4, the electrode metal 6, the conductive line 5, the semiconductor substrate 1 and the resin layer 7, and the first groove 8 is formed (FIG. 1f). At this time, since the resin layer 7 remains, it is not separated into individual semiconductor devices.

  FIG. 3 is a rear perspective view of the semiconductor substrate after the first groove 8 is formed. As shown in FIG. 3, by forming the first groove 8, the conductive line 5 is removed, and the metal film 4 and the electrode metal 6 formed between the adjacent semiconductor devices are also formed first. It remains only on the side wall of the recessed portion, and is separated for each semiconductor device and becomes an independent electrode. Therefore, if the probe is brought into contact with the electrode metal 6 exposed in such a state, the characteristic test of the semiconductor device can be performed.

  Finally, the dicing saw runs again at a depth reaching the first groove 8 along the first groove 8 from the resin layer 7 side, thereby forming a second groove 9 that completely cuts the resin layer 7 ( FIG. 1g). As a result, the semiconductor device 10 whose cross-sectional shape is shown in FIG. 4 can be formed.

  As shown in FIG. 4, in the semiconductor device 10 formed according to the present invention, the main surface of the semiconductor substrate 1 on which the circuit elements are formed is covered with the resin layer 7, and the exposed back surface (another main surface) of the semiconductor substrate 1 is exposed. ) To form protruding electrodes (bump electrodes) from which the metal film 4 and the electrode metal 6 protrude. When the semiconductor device 10 having such a structure is mounted on the mounting substrate, the protruding electrode is exposed on the side surface of the semiconductor device, so that solder rising after mounting can be visually observed, and mounting reliability can be improved. . Furthermore, since the semiconductor substrate 1 is very thin, the heat dissipation is good, and in particular, improvement in characteristics of a high-power semiconductor device is expected.

  Next, a second embodiment will be described. FIG. 5 is an explanatory view corresponding to FIG. 2 described in the first embodiment. Compared with the first embodiment, the second embodiment differs only in the shape of the recess 3. That is, the recess is formed in a T shape on the dicing line side as shown in FIG. By forming in this way, it is possible to prevent the protruding electrode from being peeled off from the inside of the recess due to an impact at the time of running the dicing saw or mounting the semiconductor device after separation. Accordingly, the recess shape may be a combination of trapezoids and circles in addition to the T shape as shown in FIG. 5, and a shape that is expected to have an anchor effect can be adopted.

  Even when the shape of the recess is changed in this way, the semiconductor device can be formed by the same manufacturing process as in the first embodiment.

  Although the present invention has been described by taking the method of manufacturing a semiconductor device made of GaAs as an example, it goes without saying that the present invention is not limited to this. For example, a semiconductor device using AlGaAs, InP, or the like as a compound semiconductor can be formed similarly.

It is explanatory drawing of the 1st Example of this invention. It is explanatory drawing of the intermediate process of the 1st Example of this invention. It is explanatory drawing of another middle process of the 1st Example of this invention. It is sectional drawing of the semiconductor device formed by this invention. It is explanatory drawing of the 2nd Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Semiconductor substrate, 2; Element area | region, 3; Concave part, 4 and 4a; Metal film, 5; Conductive line, 6: Electrode metal, 7; Resin layer, 8; ; Semiconductor device

Claims (3)

Forming a circuit element on the main surface of the semiconductor substrate;
Forming a plurality of recesses in an electrode formation scheduled region along a dicing line adjacent to an element region in which the circuit element is formed;
Forming a metal film that connects to the electrode of the circuit element and covers the inner wall of the recess;
After filling the recess with an electrode metal, covering the main surface with a resin layer;
Etching another main surface of the semiconductor substrate to expose the metal film covering the inner wall of the recess;
Along the dicing line, a part of the electrode metal filled in the recess is left on the side wall of the recess, and the resin layer, the semiconductor substrate, the electrode metal and the metal film are cut to form individual semiconductors. A method of manufacturing a semiconductor device, comprising the step of dividing the device into pieces. 2. The method of manufacturing a semiconductor device according to claim 1, further comprising: forming a metal film that covers an inner wall of the recess, and simultaneously forming a conductive line that electrically connects the metal film along the dicing line. Including
Filling the recess with the electrode metal by selectively depositing an electrode metal in the recess by the charge supplied from the conductive line;
A method of manufacturing a semiconductor device, comprising cutting the conductive line simultaneously with cutting the resin layer, the semiconductor substrate, the electrode metal, and the metal film. 3. The method of manufacturing a semiconductor device according to claim 1, wherein the step of separating the semiconductor device includes cutting at least the metal film, the semiconductor substrate and the electrode metal, or further the conductive line, A method for manufacturing a semiconductor device, comprising: cutting a part of the resin layer; and cutting the resin layer completely.

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