JPH06112312A - Manufacture of semiconductor chip - Google Patents

Abstract

PURPOSE:To prevent an electrode metal layer on the reverse side from protrud ing as burr on the side surface of each semiconductor chip in cutting a wafer applied to a water sheet for each semiconductor chip by a dicing blade. CONSTITUTION:An electrode metal layer is formed while leaving a part 5a' without an electrode metal layer which is extended in band shape at a part of each cutting line A' to each semiconductor chip out of the electrode metal layer or a number of electrode metal layers 5b in island shape where the length and width or diameter are two or less times as large a the width dimension T at a dicing blade C are formed at fine pitches.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor chip used for transistors, diodes, etc. using a silicon wafer.

[0002]

2. Description of the Related Art Conventionally, semiconductor chips (for example, mesa type semiconductor chips) used for transistors, diodes, etc. are formed by converting a plurality of semiconductor chips 1 into one silicon chip as shown in FIGS. After being formed on the front surface of the manufactured wafer A, a collector and cathode electrode metal film 5 of silver or the like is formed on the entire back surface of the wafer A,
Then, a wafer sheet B made of a soft synthetic resin is attached to the back side of the wafer A, and then the wafer A is
Manufactured by a method of separating each semiconductor chip 1 by cutting with a rotary dicing blade C of a grinding wheel along a cutting line A ′ passing through the groove (mesa groove) 2 between the semiconductor chips 1. is doing.

Reference numeral 3 indicates a glass film coated and formed in the groove (mesa groove) 2, and reference numeral 4 indicates an anode electrode metal film such as silver formed on the upper surface of the wafer 1.

[0004]

By the way, in this manufacturing method, when the wafer A is cut into individual semiconductor chips 1 by the rotary type tying blade C,
The dicing blade C penetrates the electrode metal film 5 formed on the back surface of the wafer A so as to reach the wafer sheet B on the back surface side thereof so that the electrode metal film 5 is also cut. There must be.

However, since the lower surface side of the electrode metal film 5 is supported by the wafer sheet B made of a soft synthetic resin, the electrode metal film 5 is cut by the timing blade C of the grinding wheel. At this time, the electrode metal film 5 is forcibly scraped off while rubbing the electrode metal film 5 with the dicing blade C.
Therefore, the semiconductor chip 1 is cracked as shown by the symbol D, and the yield rate is lowered.

Moreover, since the electrode metal film 5 is forcibly removed by the dicing blade C, the electrode metal film 5 cannot be sharply cut, and the electrode metal film 5 formed over the entire lower surface of the wafer A. A portion of the dicing blade C having a thickness T remains in a state of being protruded from a cutting surface of the dicing blade C, that is, a side surface of the semiconductor chip 1. In other words, from one side surface of each semiconductor chip 1, the electrode metal is formed. As shown in FIG. 6, a part of the film 5 remains in a state of protruding by a dimension substantially equal to the thickness T of the dicing blade C, and this part becomes a wide burr 5 ', and
When the semiconductor chip 1 is die-bonded to the lead frame or the like, the wide burrs 5'impede the bonding of the semiconductor chip 1 to the lead frame or the like, or the semiconductor chip 1 is tilted. There was also a problem that induces.

[0007] In particular, these problems are to maintain the durability of the dicing blade C when the glass film 3 in the mesa groove 2 is cut by the dicing blade C in the manufacture of the mesa type semiconductor chip. Moreover, when the thickness T is increased, it is further increased. The present invention, when manufacturing a semiconductor chip,
It is a technical object to provide a manufacturing method capable of reliably reducing the occurrence of the above problems.

[0008]

In order to achieve this technical object, the present invention firstly comprises a step of forming a large number of semiconductor chips on the front surface of a wafer and an electrode metal film on the back surface of the wafer. In the manufacturing method, which comprises a step of forming, a step of attaching a synthetic resin wafer sheet to the back surface side of the wafer, and a step of cutting the wafer into semiconductor chips for each semiconductor chip, the electrode metal layer is formed. In the electrode metal layer, a portion without an electrode metal layer extending in a strip shape having an appropriate width along each cutting line is formed at a position of each cutting line for each semiconductor chip.

Secondly, according to the present invention, a step of forming a large number of semiconductor chips on the front surface of the wafer, a step of forming an electrode metal film on the back surface of the wafer, and a synthetic resin on the back surface side of the wafer. In the manufacturing method, which comprises a step of adhering a wafer sheet made of metal and a step of cutting the wafer into individual semiconductor chips by a dicing blade, the electrode metal layer is diced in a length dimension and a width dimension or a diameter dimension. It was decided to form an island-shaped electrode metal layer having a width equal to or less than twice the width dimension of the blade, and a large number of the electrode metal layers arranged all over the back surface of the wafer at fine pitch intervals.

[0010]

[Operation] By configuring as in the first invention,
When the wafer is cut into individual semiconductor chips with a dicing blade, the portion of the wafer on the back surface of which there is no strip-shaped electrode metal layer is cut along the longitudinal direction of the strip-shaped portion without the electrode metal layer. Since it is possible to significantly reduce the damage to each semiconductor chip when cutting the wafer,
Under the condition that the electrode metal layer is secured on the back surface of each semiconductor chip, a part of the cathode electrode metal layer protrudes in a burr shape on the cut surface by the dicing blade, that is, the side surface of each semiconductor chip. It can be eliminated or the protruding burr can be reduced.

Further, according to the second aspect of the invention, when the wafer is cut into individual semiconductor chips by the dicing blade, the electrode metal layer on the back surface side of the wafer is divided into islands. By doing so, it is possible to significantly reduce the damage to each semiconductor chip when the wafer is cut, and moreover, the dicing blade contacts the island-shaped electrode metal layer with a part of the thickness dimension of the dicing blade. In this case, the electrode metal layer in this portion remains as a burr, but when it is in contact with the entire thickness dimension of the dicing blade, the island-shaped electrode metal layer is removed by the dicing blade. By the action, it peels from the back surface of the semiconductor chip and is removed. Since thus, the cut surface by the dicing blade, i.e., the maximum length of a burr projecting from the side surface of each semiconductor chip, it can be made smaller than the thickness of the dicing blade.

[0012]

Therefore, according to the present invention, it is possible to surely improve the yield rate when a wafer is cut into individual semiconductor chips with a dicing blade, and to perform die bonding when the semiconductor chips are die-bonded to a lead frame. This has the effect of reliably reducing bonding mistakes.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. 1 and 2 show a first embodiment. In this figure, reference numeral 1 denotes a wafer, and this wafer 1 has
A plurality of semiconductor chips 1 are formed on the surface thereof, and a glass film 3 is formed in the mesa groove 2 between the semiconductor chips 1.
And an electrode metal layer 4 for an anode is formed on the upper surface of each semiconductor chip 1.

Next, the above-mentioned wafer A is adhered to a wafer sheet B made of a soft synthetic resin after forming an electrode metal layer 5a for the cathode on the back surface thereof.
Are cut by the rotary dicing blade C of the grinding wheel along a cutting line A ′ passing through the mesa groove 2 between the semiconductor chips 1 to separate the semiconductor chips 1. When forming the electrode metal layer 5a on the back surface of the wafer A, the electrode metal layer 5a is not formed on the entire back surface of the wafer A as in the conventional case, but the wafer A is formed on each semiconductor chip 1 The electrode metal layer-less portion 5a 'extending in a strip shape having an appropriate width dimension E along each cutting line A'is formed at each cutting line A'for cutting.

The electrode metal layer-less portion 5a 'extending in a strip shape can be formed simultaneously when the electrode metal layer 5a is formed, and after the electrode metal layer 5a is formed over the entire back surface of the wafer A. Alternatively, a part of the electrode metal layer 5a may be removed by etching in a photoresist process or may be cut off by polishing with a dicer.

With this configuration, when the wafer A is cut by the dicing blade C into individual semiconductor chips 1, the strip-shaped electrode metal layer-free portion 5a 'on the back surface of the wafer A is Since it is possible to cut along the longitudinal direction of the strip-shaped electrode metal layer-less portion 5a ', damage to each semiconductor chip 1 when the wafer A is cut can be greatly reduced.

Moreover, a part of the cathode electrode metal layer 5a is projected in a burr shape on the cut surface by the dicing blade C, that is, on the side surface of each semiconductor chip 1.
The width can be reduced by the width E of the strip-shaped electrode metal layer-free portion 5a '. In this case,
By making the width dimension E of the strip-shaped electrode metal layer-less portion 5a 'equal to or larger than the thickness dimension T of the dicing blade C, there is no burr protruding from the side surface of each semiconductor chip 1. You can do it.

3 and 4 show a second embodiment. In the second embodiment, when the electrode metal layer for the cathode is formed on the back surface of the wafer A, the length dimension L and the width dimension W of the electrode metal layer are set to the width dimension T of the dicing blade C. The island-shaped electrode metal layer 5b which is doubled or less in number is formed to have a large number of electrode metal layers 5b arranged at fine pitch intervals over the entire back surface of the wafer.

With this structure, when the wafer A is cut into individual semiconductor chips 1 by the dicing blade C, the electrode metal layer on the back surface side of the wafer A is divided into island-shaped electrode metal layers 5b. By doing so, the damage to each semiconductor chip 1 when the wafer A is cut can be significantly reduced as compared with the conventional case where the electrode metal layer is continuously formed over the entire back surface of the wafer.

Moreover, the dicing blade C contacts a part of the thickness T of the dicing blade C with respect to the island-shaped electrode metal layer 5b, as shown in FIGS. 4 (C) and (D). In this case, the electrode metal layer in this portion remains as a burr without being cut by the dicing blade C, but as shown in FIGS. When the island-shaped electrode metal layer 5b is in contact with the entire size T, the island-shaped electrode metal layer 5b is removed from the back surface of the semiconductor chip 1 by the scooping action of the dicing blade C. The maximum length of the burr protruding from the side surface of each semiconductor chip 1 cut by the blade C, that is, in the dicing blade C It can be made smaller than the dimension T.

According to an experiment conducted by the present inventor, when the length dimension L and the width dimension W of the island-shaped electrode metal layer 5b are set to be larger than twice the width dimension T of the dicing blade C, dicing is performed. Blade C
When the island-shaped electrode metal layer 5b is in contact with the island-shaped electrode metal layer 5b over the entire thickness T of the dicing blade C, as shown in FIGS. It was not possible to peel and remove it from the back surface of No. 1.

The island-shaped electrode metal layers 5 are formed.
The dimension E ′ of the gap (the portion without the electrode metal layer) between b should be as narrow as possible in the sense of reducing the resistance value in the electrode metal layer on the back surface side of each semiconductor chip 1. , A vertical pitch interval obtained by adding the length dimension L of each island-shaped electrode metal layer 5b to the gap dimension E ', and a lateral width obtained by adding the width dimension W of each island-shaped electrode metal layer 5b to the gap dimension E'. The pitch interval in the direction should be set to 1 or less of 10 of the length dimension and the width dimension of the semiconductor chip 1 in order to reduce the resistance value of the electrode metal layer on the back surface side of each semiconductor chip 1 as much as possible. Met. According to a preferred example, when the length dimension of the semiconductor chip 1 is 1000 μm and the thickness dimension T of the dicing blade C is 50 μm, the length dimension L of the island-shaped electrode metal layer 5b is 50 μm. The gap dimension E'is 5
It was good to set it to 25 microns.

[Brief description of drawings]

FIG. 1 is an enlarged plan view of a wafer showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is a partially enlarged plan view of a wafer showing a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG.

FIG. 5 is a perspective view showing a conventional method.

6 is an enlarged sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

 A Wafer A'Cutting line B Wafer sheet C Dicing blade 1 Semiconductor chip 5a Electrode metal layer 5a 'No electrode metal layer portion 5b Island-shaped electrode metal layer

Claims (2)

[Claims] 1. A step of forming a large number of semiconductor chips on the front surface of a wafer, a step of forming an electrode metal film on the back surface of the wafer, and a wafer sheet made of synthetic resin being attached to the back surface side of the wafer. Process,
In a manufacturing method, which comprises a step of cutting the wafer into individual semiconductor chips with a dicing blade,
Forming the electrode metal layer at a position of each cutting line for each semiconductor chip in the electrode metal layer, leaving a portion without an electrode metal layer extending in a strip shape with an appropriate width along each cutting line. A method for manufacturing a characteristic semiconductor chip. 2. A step of forming a large number of semiconductor chips on the front surface of the wafer, a step of forming an electrode metal film on the back surface of the wafer, and a wafer sheet made of synthetic resin being attached to the back surface side of the wafer. Process,
In a manufacturing method, which comprises a step of cutting the wafer into individual semiconductor chips with a dicing blade,
The electrode metal layer is formed into an island-shaped electrode metal layer having a length dimension and a width dimension or a diameter dimension less than or equal to twice the width dimension in the dicing blade, and a large number of the electrode metal layers are arranged at a fine pitch interval over the entire back surface of the wafer. A method of manufacturing a semiconductor chip, which is characterized in that the semiconductor chip is formed in the arranged one.