JP4859716B2 - Wafer and its transfer system - Google Patents

Description

  The present invention relates to a wafer and its transfer system, and more particularly to a wafer having a small thickness and its transfer system.

  In recent years, thinning of semiconductor devices has been promoted in order to meet demands such as reduction of on-resistance and improvement of mounting density, and in particular, semiconductor devices with a thin substrate have been promoted.

-Manufacturing method of semiconductor device according to first prior art-
First, as shown in FIG. 12, a wafer 102a having an element region 101 formed on the main surface is prepared, and a protective tape 105a is attached to the surface of the wafer 102a.

  Next, as shown in FIG. 13, the front surface of the wafer 102a is fixed to the grinding fixture 107, and the wafer 102a is ground and thinned from the back surface to a desired thickness. Specifically, in the case of a discrete device, the wafer 102a is ground to have a film of about 100 to 200 μm, and in the case of LSI, the wafer 102a is ground to have a film of about 150 to 330 μm. After grinding, the protective tape 105a is peeled from the wafer 102a.

  Next, as shown in FIG. 14, a flat ring 105c to which the fixing tape 105b is attached is prepared, and the back surface of the wafer 102a is fixed to the fixing tape 105b exposed from the flat ring 105c. Then, the flat ring 105c and the fixing tape 105b are fixed to the dicing table 103, and the wafer 102a is fully diced with a dicing blade to cut and separate the wafer 102a into each chip 102b.

  Next, as shown in FIG. 15, each chip 2b is picked up from the fixing tape 105b, the conductive material 113 is applied onto the island 112a, and the chip 102b is mounted. The element region 101 and the lead 112b are connected by, for example, a wire 114. Note that the chip 102b, the island 112a, and the wire 114 are sealed with, for example, resin.

  However, in the manufacturing method, when the wafer 102a is ground to the thickness of the chip, the wafer 102a is greatly warped. In particular, in recent years, the diameter of the wafer 102a has been increased, and this warpage cannot be ignored.

  Therefore, the following manufacturing method has been disclosed in order to prevent the wafer from warping.

-Manufacturing method of semiconductor device according to second prior art-
First, as shown in FIG. 16, a wafer 202a having an element region 201 formed on the front surface side is prepared, and the back surface of the wafer 202a is adsorbed and fixed to a dicing table 203 by vacuum or the like. Then, the groove portion 204 is formed by half dicing the surface of the wafer 202a.

  Next, as shown in FIG. 17, a flat ring 205b to which a protective tape 205a is attached is prepared. Then, the element region 201 is fixed to the protective tape 205a exposed from the flat ring 205b.

  Next, as shown in FIG. 18, the flat ring 205b is adsorbed and fixed to the grinding fixing base 207 of the grinding apparatus. Then, the wafer 202a is ground and thinned until it reaches the groove portion 204 from the back surface side. At this time, the wafer 2a is divided into individual chips 202b.

  Next, each chip 2b is picked up from the fixed tape 105b, and a semiconductor device as shown in FIG. 15 is obtained in the same manner as in the first prior art.

  As described above, in the second conventional technique, when the wafer 202a is thinned, the wafer 202a is separated into individual chips 202b, so that warpage of the wafer 202a is suppressed.

Examples of related technical literatures include the following patent literatures.
JP 2000-195826

  However, in the first and second prior arts, after the wafers 102a and 202a are separated into the chips 102b and 202b, the chips 102b and 202b have to be picked up and transferred to the next process. . This is because the mechanical strength of the fixed tape 105b and the protective tape 205a is weak.

  In the above manufacturing process, the back electrode is not formed on each of the chips 102b and 202b, and the chip is mounted on the island 112a by the conductive material 113. In the first and second prior arts, the fixing tape 105b and the protective tape 205a cannot withstand the processing temperature at the time of forming the back electrode. This is because it is difficult to form the back electrodes together while being attached to the tape 205a.

  In the second prior art, the wafer 202a is separated into individual chips 202b at the same time as grinding. However, since the mechanical strength of the protective tape 205b is weak, it is difficult to thin the chips 202b to 80 μm or less. Met.

In view of the above, a wafer transfer system according to the present invention provides a wafer having an element region formed on a surface thereof, and the wafer is attached to a rigid support through an adhesive layer and surrounds the element region. The groove is formed into individual pieces, and the groove is embedded so that the adhesive layer is lower than the wafer , and the side wall of the groove has a narrow width at the upper end of the groove. The electrode material is deposited so as to cover the back surface of the wafer and the adhesive layer in the groove, and the wafer is transported to the case. It is characterized by being transported in a container.

The wafer according to the present invention is a wafer having an element region formed on a surface thereof, and the wafer is attached to a rigid support through an adhesive layer, and a groove is formed so as to surround the element region. The groove portion is embedded so that the adhesive layer is lower than the wafer , and the side wall of the groove portion is curved so that the width of the upper end portion of the groove portion is narrowed. The electrode material is deposited so as to cover the back surface of the wafer and the adhesive layer on the groove, and is sealed in a transfer case. It is characterized by.

  In the present invention, after the wafer is thinned into individual pieces, the wafer can be transported while being attached to the support.

  Furthermore, the back electrode can be formed while the wafer is attached to the support. In this case, the back electrode prevents moisture in the air from being mixed into the adhesive layer.

  Hereinafter, specific embodiments of the present invention will be specifically described with reference to the drawings.

―Outline of manufacturing method―
First, as shown in FIG. 1, a wafer 2 a having an element region 1 formed on the surface side is prepared, and a groove portion 4 is formed so as to surround the element region 1. At this time, the groove 4 is formed so as to be deeper than at least the film thickness of the completed chip.

  Next, as shown in FIG. 2, the wafer 2 a is bonded to the support 5 with the adhesive layer 6 with the element region 1 facing down. Here, the adhesive layer 6 is made of a viscous material such as an epoxy resin, a resist, or acrylic. The support 5 is made of a rigid material such as glass, quartz, ceramic, plastic, metal, or resin. The adhesive layer 6 is formed so as not to completely fill the groove 4 and to be slightly shallower than the completed chip thickness.

  Next, as shown in FIG. 3, a BG tape 7 is attached to the support 5, and the wafer 2a is ground and thinned from the back surface side to a desired film thickness (corresponding to the chip film thickness after completion). At this time, the wafer 7 a is ground up to the groove portion 4 to be divided into individual chips 2 b, and the wafer 2 a is firmly supported by the rigid support 5. For this reason, in this embodiment, the wafer 2a can be ground to 80 μm or less. When the wafer 2a is separated into individual chips 2b, the grooves 4 are exposed. However, since the adhesive layer 6 enters the grooves 4, the impurities of grinding are mixed into the element region 1 from the grooves 4. Can be suppressed.

  Next, as shown in FIG. 4, an electrode material 4 such as Al or Cu is deposited from the back side of each chip 2b by using a method such as a CVD method, a PVD method, a sputtering method, or a plating method. Form. In this embodiment, since each chip 2b is supported by the support body 5 with high heat resistance, it is possible to process the back surface together without separating the chips 2b from the support body 5.

  Next, as shown in FIG. 5, when each chip 2 b is affixed to the fixing tape 16 and the adhesive layer 6 is dissolved, each chip 2 b is separated from the support 5.

  Next, as shown in FIG. 6, each chip 2b is picked up from the fixed tape 16 and mounted on the island 12a. An electrode (not shown) formed in the element region 1 and the lead 12b are connected by a wire 14 such as gold or copper. Further, if necessary, the chip 2b, island 12a, and lead 12b are molded with resin to complete the semiconductor device.

-Details of the process of forming the groove 4 in the wafer 2a (Fig. 1)-
In the present invention, as a method for forming the groove 4 in the wafer, various methods are applied as follows.

  For example, the groove 4 may be formed by half dicing. In this case, the half dicing is performed by a blade, a laser, or the like. In particular, when half dicing is performed by a laser, even if a layer having low mechanical strength such as a low-k (low dielectric constant) material is formed on the wafer 2a, peeling of this layer can be prevented.

  The groove 4 may be formed by etching such as isotropic etching or anisotropic etching. In this case, the groove portion 4 can be formed so as to have a shape such that the electrode material 8 hardly adheres to the side wall of the groove portion.

That is, as shown in FIG. 7A (enlarged view in the vicinity of the groove 4a), by using isotropic etching, the groove 4a can be curved so that the upper end is narrowed. At this time, the electrode material 8 is difficult to adhere to the side wall of the groove 4a. Further, as shown FIG. 7 (b), the use of the technique of repeating the plasma deposition process mainly using the plasma etching step and primarily C ₄ F ₈ gas using SF ₆ gas as an anisotropic etching alternately Then, the groove part 4b can be formed so that an inner wall may be wave-like roughened. At this time, the electrode material is attached so as to be interrupted on the inner wall of the groove 4b.

-Details of the process of attaching the support 5 to the wafer 2a (Fig. 2)-
In the embodiment, the back electrode 9a is formed in a state where each chip 2b is attached to the support 5 (FIG. 4). At this time, if the adhesive layer 6 is completely embedded in the groove 4, the electrode material 8 is formed without interruption between the chip 9 a and the adhesive layer 6 exposed in the groove 4, thereby dissolving the adhesive layer 6. Even if it tries (FIG. 5), the chip | tip 2b remains connected with the electrode material 8, and cannot melt | dissolve. For this reason, it is necessary to form the adhesive layer 6 so as to be lower than the thickness of the completed chip 2b.

  That is, when the adhesive layer 6 is first applied to the support 5 and then the wafer 2 a is attached, the adhesive layer 6 is pushed out by the air accumulated in the groove 4. Therefore, it becomes difficult for the adhesive layer 6 to completely enter the groove portion 4.

  On the other hand, when the support layer 5 is pasted after the adhesive layer 6 is first applied to the wafer 2 a, the adhesive layer 6 enters the groove 4 when it is applied to the adhesive layer 6. Therefore, the adhesive layer 6 is easier to fill the groove portion 4 than the above-described method. Thereby, this method is effective when the wettability of the groove part 4 is large, for example, the diameter of the groove part 4 is small.

-Details of grinding process of wafer 2a (Fig. 3)-
In the above embodiment, the wafer 2a is ground and simultaneously separated into chips 2b. Thereafter, each chip 2b is transported to the next process while being attached to the support 5, and at this time, the chip 2b is easily chipped at the end of the back surface. In order to prevent this, a step of forming roundness at the end of the chip 2b may be added. Specifically, after the wafer 2a is ground, the back surface of the wafer 2a may be slightly etched using, for example, an acid (for example, a mixed solution of HF and nitric acid) as an etchant.

-Details of the process of forming the back electrode 9a (Fig. 4)-
In the above embodiment, when the adhesive layer 5 is dissolved, each chip 2b is separated from the support 5 (FIG. 5). This is because the electrode material 8 is formed discontinuously on the chip 2b and the adhesive layer. Because. Hereinafter, the discontinuity of the electrode material 8 will be described in detail.

Figure 8 (a), (b) is a sectional view enlarging a vicinity of the groove 4. In the present embodiment, the back electrode 9a is formed not only on the back surface of the chip 2b but also on the upper end of the side wall portion thereof, so that this serves as an umbrella and the electrode material 8 is formed on the side wall of the chip 2b. It is difficult to adhere to the parts 4a and 4b. As a result, the electrode material 8 is not formed at all on the side wall portion 4a as shown in FIG. 8A, or is thinly formed on the side wall portion 4b as shown in FIG. 8B.

  Further, since the adhesive layer 4 is embedded in the groove 4, the electrode material 8 is formed so as not to extend to the element region 1, and a defective product such as a short circuit is unlikely to occur.

-Details of dissolution process of adhesive layer (Fig. 5)-
In order to dissolve the adhesive layer 5, it is necessary to mix the dissolving agent 17 into the adhesive layer 5, and specific examples thereof will be described below.

The support 5 shown in FIG. 9B has dissolution holes 11 for supplying the dissolution agent 17. If this support body 5 is used, as shown in FIG. 9 ( a ), the adhesive tape 6 is dissolved by sticking the fixing tape 16 to the back surface of each chip 2 b and supplying the dissolution agent 17 from the dissolution holes 11 a. Each chip 2b can be peeled off from the support 5.

  Further, in FIG. 10A, a dissolution hole 11 b for supplying the dissolution agent 17 to the fixing tape 16 is formed. For this reason, each chip | tip 2b can be peeled from the support body 5 by supplying the melt | dissolution agent 17 from the melt | dissolution hole 17 of the fixing tape 16. FIG.

  In FIG. 10B, each chip 2b is sucked and fixed by the suction machine 18. In this case, since the dissolving agent 17 is sucked, it is supplied to the adhesive layer 6 from a gap in the side wall of the groove portion 4, for example.

-Details of semiconductor device structure (Fig. 6)-
In the embodiment, the back electrode 9b is formed not only on the back surface of the chip 2b but also on the side wall. Thus, when the back electrode 9b and the island 12a are connected via the conductive material 13a such as solder and the reflow process is performed, the conductive material 13a flows toward the outside of the chip 2b. Therefore, the conductive material 13a forms the side fillet 13b, and the chip 2b and the island 12a are firmly connected.

-Transport of wafer 2a-
In general, in the manufacture of a semiconductor device, not all processes are performed in the same place. For example, a pre-process is performed in Japan and a post-process is performed in Asia. In particular, the process of processing the wafer 2a and the process of mounting the chip 2b are often performed at different locations.

  In this regard, in the present invention, after processing the wafer 2a, the chip 2b can be transported while being attached to the support 5.

  That is, as shown in FIG. 11, after the back surface electrode 9a is formed on each chip 2b, it can be put into the transfer case 15 as it is and transferred to another process.

  This is because the support 5 has rigidity, and the wafer 2a is separated into chips, so that warpage hardly occurs.

  Further, the adhesive layer 6 is covered with the electrode material 8 in the groove 4. For this reason, it is difficult for moisture in the air to be mixed into the adhesive layer 6 at the time of transportation, and the problem that each chip 2b peels off at the time of transportation hardly occurs.

  For the transport case 15, various types such as a laminate bag and a solid box are applied. And if the dry agent 19 which absorbs the water | moisture content in the air is put in the conveyance case 15, peeling of the contact bonding layer 6 can be prevented more firmly.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, the present invention is not limited by the type of the chip 2b, and can be applied to various semiconductor devices such as LSIs as well as discrete devices such as MOS transistors, IGBTs, and diodes.

Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. 1 is a cross-sectional view of a semiconductor device according to the present invention. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on this invention is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on a prior art is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on a prior art is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on a prior art is shown. Sectional drawing of the semiconductor device which concerns on a prior art is shown. Sectional drawing of the semiconductor device which concerns on a prior art is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on a prior art is shown. Sectional drawing of 1 process of the manufacturing method of the semiconductor device which concerns on a prior art is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Element area | region 2a Wafer 2b Chip 3 Dicing stand 4 Groove part 4a Side wall part 4b Side wall part 5 Support body 6 Adhesive layer 7 BG tape 8 Electrode material 9a Back surface electrode 9a Electrode side wall part 10a Side wall part 10b Side wall part 11 Melting hole 12a Island 12b Lead 13a Conductive material 13b Side fillet 14 Wire 15 Carrying case 17 Solvent 18 Suction machine 19 Drying agent 101 Element region 102a Wafer 102b Chip 103 Dicing table 105a Protection tape 105b Fixing tape 105c Flat ring 107 Grinding fixing table 112a Island 112b Lead 113 Conductive paste 114 Wire 201 Element region 202a Wafer 202b Chip 203 Dicing table 204 Groove 205a Protective tape 205b Flat ring 207 Grinding fixing table

Claims (16)

Prepare a wafer with a device area on the surface,
The wafer is bonded to a rigid support through an adhesive layer, and a groove is formed so as to surround the element region, and the wafer is separated.
The groove is embedded such that the adhesive layer is lower than the wafer ,
The side wall of the groove is formed so as to be curved or rough so that the width of the upper end of the groove is narrow,
An electrode material is deposited so as to cover the back surface of the wafer and the adhesive layer in the groove, and the wafer is transferred in a transfer case. The wafer transfer system according to claim 1, wherein the electrode material is formed so as to extend from a back surface of the wafer to an upper end of a side end portion of the wafer. The electrode material, a wafer transfer system according to claim 1 or 2, characterized in that the functions as the moisture in the air from entering into the adhesive layer. It said wafer is a wafer transfer system according to any one of claims 1 to 3, characterized in that a film thickness of not more than 80 [mu] m. Wherein the support, the wafer transfer system according to any one of claims 1 to 4, characterized in that the dissolution holes for dissolution agent enters dissolving the adhesive layer after conveyance is formed. Wafer transfer system according to any one of claims 1 to 5, wherein the transport case, characterized in that the dry agent for removing the water is contaminated. The wafer transfer system according to claim 1, wherein the transfer case includes a laminate bag or a solid box. The support wafer transfer system according to any one of claims 1 to 7, wherein glass, quartz, ceramic, plastic, metal, be composed of any of a resin. A wafer having an element region formed on the surface,
The wafer is bonded to a rigid support through an adhesive layer, and a groove is formed so as to surround the element region, and the wafer is separated.
The groove is embedded such that the adhesive layer is lower than the wafer ,
The side wall of the groove is curved so that the width of the upper end of the groove is narrow, or is formed to be rough like a wave, and covers the back surface of the wafer and the adhesive layer in the groove. An electrode material is deposited as described above, and the wafer is sealed in a transfer case. The wafer according to claim 9, wherein the electrode material is formed so as to extend from a back surface of the wafer to an upper end of a side end portion of the wafer. The wafer according to claim 9 or 10 , wherein the electrode material functions so that moisture in the air does not enter the adhesive layer. Said wafer is a wafer according to any one of claims 9-11, characterized in that the following thickness 80 [mu] m. The wafer according to any one of claims 9 to 12 , wherein a dissolution hole for supplying a dissolving agent that dissolves the adhesive layer is formed in the support. Wafer transfer system according to any of claims 9-13 wherein the transport case, characterized in that the dry agent for removing the water is contaminated. The carrying case is a wafer transport system according to any of claims 9-14, characterized in that it consists of a laminate of the bag or solid box. The support wafer according to any one of claims 9 to 15, glass, quartz, ceramic, plastic, metal, be composed of any of a resin wherein.