JPH02185049A - Semiconductor element - Google Patents

Abstract

PURPOSE:To enable wire bonding by recognizing a picture even when deviation in the direction of rotation is generated by forming a sign for recognizing the picture in an annular type pattern or an approximately annular type pattern having a notch region and shaping metallic electrodes to both the inside and the outside of the sign for recognizing the picture. CONSTITUTION:Metallic electrodes 5 for connecting lead wires have a sign 7 for recognizing a picture, the sign 7 is formed in an annular type pattern or an approximately annular pattern having notch regions in a plan view, and the metallic electrodes 5 are shaped on both the inside and the outside of the sign 7 for recognizing the picture. Consequently, even when a semiconductor element is fixed deviated in the direction of rotation to a support plate, etc., the sign 7 for recognizing the picture can be obtained as an annular type picture. Accordingly, even when deviation in the direction of rotation is generated, a wire bonder having a picture recognition function is used on the semiconductor element getting no trouble in wire bonding, and wire bonding operated at high speed and having little 'regognition impossibility' is conducted.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor device having an image recognition mark.

[Prior Art] A glue door alfM for electrically connecting an electrode on a semiconductor element (#-conductor chip and an external lead) is wire-bonded by a well-known automatic wire bonder.

[Problem to be solved by the invention] In wire bonding, in order to accurately connect the thin lead wires between the electrodes on all the semiconductor chips and the external leads, the bonding head of the wire bonder (the part that applies pressure to the lead m wires) is required. One requirement is accurate placement of the electrodes on all semiconductor chips.

Conventionally, for semiconductor chips such as rectifier diodes with relatively large electrodes, the semiconductor chip is accurately positioned and fixed on the support plate of a lead frame, and the lead frame is intermittently conveyed at a predetermined pitch. This was achieved by placing the electrodes on the chip precisely below the bonding head. However, according to the above method,
The accuracy of positioning the semiconductor chip on the support plate is the key! However, due to the connection accuracy (bonding accuracy) of wire bonding, it is difficult to perform highly accurate wire bonding. Therefore, when the semiconductor chip becomes smaller and fc is used, or when wire bonding is performed to a thin lead wire at a position offset to one side of the semiconductor chip, the positional accuracy of bonding may become insufficient. In addition, since wire bonding is performed without recognizing the semiconductor chip, unnecessary wire bonding will be performed on the support plate to which the semiconductor chip is not fixed due to some kind of spraying. This is disadvantageous in terms of productivity. A possible solution to the above problem is to use a wire bonder with an image recognition function. That is, this method detects the position of the semiconductor chip by recognizing the image recognition mark provided on the semiconductor chip with pre-stored image data on a pattern match lag, and then performs wire bonding. According to this method, wire bonding with high connection accuracy is possible, and wire bonding is not performed on a support plate to which a chip is not fixed. By the way, in the case of mass production of semiconductor chips fixed to the support plate,
The semiconductor chip may be fixed to the support plate with rotational deviation relative to its standard position. In this case, the image recognition mark is also displaced in the rotational direction. By the way, in the case of a single-electrode rectifier diode tip, etc., if the wire bonding position is correct, the deviation in the rotational direction will not cause any trouble to the wire bonding. In the past, it is desirable to perform wire bonding on semiconductor chips that are only offset in the rotational direction. However, the commonly used "◇"
With shape image recognition markers, if the marker is deviated in the direction of rotation, image recognition cannot be performed, and therefore wire bonding may not be possible. Of course, if the position of the semiconductor chip in the rotational direction is also detected, image recognition becomes possible, but this increases the recognition time and is disadvantageous in terms of increasing the speed of wire bonding.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor element that can be wire-bonded by image recognition even when deviation in the rotational direction occurs.

Means for Solving the Problem] The first invention of the present application for achieving the above object is that a metal electrode for connecting a thin lead wire is formed on one main surface of a semiconductor substrate, and The metal electrode is provided with a mark for image recognition, and the mark for image recognition is formed in a circular pattern or a substantially circular pattern having a cutout area when viewed from above, and the gold a'g electrode is provided with a flat surface. visually, it is provided both inside and outside the image recognition mark.
- It is related to a characteristic semiconductor element.

A second invention of the present application for achieving the above object is that a metal electrode is formed on one main surface of a semiconductor substrate, the metal electrode is provided with an image recognition mark, and the image recognition The mark is located at the center of the metal electrode, and has a circular or substantially annular planar shape, and one outer part and the other outer part of the image recognition mark of the metal electrode. The present invention relates to a semiconductor device characterized in that the area is a connection area for thin lead wires.

[Function] # of the 111th invention! - The image recognition mark of the conductor element has a circular pattern or a substantially circular pattern.

Therefore, even if the semiconductor element is fixed to the support plate or the like while being deviated in the rotational direction, the image recognition mark can be captured as an annular image. For this reason,
In the case of semiconductor devices that do not interfere with wire bonding even when deviation occurs in the rotational direction, wire bonding can be performed at high speed and with fewer "unrecognizable j" using a wire bonder having an image recognition function.In addition, the image recognition function 1 Since there are electrodes that function as bonding pads in both the inner region and the outer region of the sensor, there is virtually no reduction in the effective area of the electrodes due to the provision of the image recognition mark. Naturally, missing parts are also detected, so unnecessary wire bonding is not performed on the support plate where the semiconductor element is missing.

In the semiconductor device of the second invention, since the planar shape of the image recognition mark is circular, approximately circular, or annular,
Even when it is deviated in the rotational direction, the image recognition mark can be identified as a circular or annular image. Therefore, even when the semiconductor element is bent and fixed in the rotational direction with respect to the support plate, image recognition can be performed at high speed and with fewer unrecognizable images.

Furthermore, a mark for image recognition is placed approximately in the center of the metal electrode7.
- The metal electrode around the image recognition mark can be used as a connection part for the thin lead wire. Therefore, the thin lead wires can be connected to both sides of the image recognition sign with high positional accuracy.
The current distribution in these thin lead wires and the semiconductor element is improved, and the allowable current value can be increased satisfactorily.

[First Embodiment] Next, a rectifying element and a method for manufacturing the same according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

As shown in FIG. 2, the diode tip 11 has an anode electrode (seventh main electrode) on one main surface of a silicon semiconductor substrate 4 consisting of an n-shade region 1, an n-shade region 2, and a p-shade region 6.
5, and a cathode electrode @! on the other main surface. (Second life'!
1L pole) 6. Both the anode electrode 5 and the cathode electrode 6r/i have a substantially square planar shape,
They are formed on almost the entire surface of one main surface and the other main surface of the semiconductor substrate 4, respectively, except for the edges. Anode electrode 5
consists of aluminum electrodes, to which thin lead wires are connected as described below. The cathode electrode 6 is made of a two-layer electrode made of titanium and nickel, and is fixed to one main surface of the support plate. This embodiment differs from the conventional example in that an image recognition mark 7 is formed on the anode electrode 5, and in the planar shape of the image recognition mark R7. The image recognition mark 7 consists of a non-electrode portion in which one main surface of the semiconductor substrate 4 is exposed, without forming the anode electrode 5 on the one main surface of the semiconductor substrate 4. The image recognition mark 7 of this embodiment is formed by forming the anode electrode 5 over the entire surface by vacuum deposition and then removing a part of the anode electrode 5 by etching or the like. As shown in FIG. 1, the image recognition sign 7
is formed approximately at the center of the anode electrode 5, that is, approximately at the center of the semiconductor substrate 4, and has a substantially annular planar shape. However, the image recognition mark 7 does not have a completely closed annular pattern, but has a notched area. The cutout area of the annular pattern is the remaining portion 8 of the end node electrode 5. Therefore, the image recognition mark 7 is divided by the remaining portion 8 of the anode electrode 5. The anode electrode 5 is formed on both the inside and outside of the image recognition mark 7, and the two are electrically connected through the remaining portion 8.

Next, a method of wire bonding using this image recognition mark 7 will be explained. FIG. 6 conceptually shows the configuration of automatic wire bonding. This automatic wire bonder includes a bonding stage 10 on which a support plate 9 to which a diode tip 11 is fixed, a lighting device 12, and a black and white TV.
Left camera 6, bonding tool 14, and moving mechanism 1
5, an image reading device 16, and a computer 17.

The moving mechanism 15 includes a lighting device 12, a camera 13, and a tool 1.
4 and is movable relative to the stage 1o,
By the control of a computer 17 with peripheral equipment
Move to the target position.

To perform wire bonding, first, as shown in FIG. 5, a lead frame 18 for a seven-tap type rectifier consisting of a support plate 9 and external leads 24 is prepared, and the diode chip 11 is fixed on the support plate 9. . Next, the lead frame 18 is set at a predetermined position on the bondi fern stage 100. TV right camera 3I'i, preset settings,
An area 20 shown surrounded by a dotted line in FIG. 1 is projected, which definitely includes the reference point to be determined by image recognition. In addition, FIG. 1 depicts a case where the diode chisage 11 is deviated from the standard position in the vertical, horizontal, and rotational directions.

This analog image data is then A-D converted back into 256-level digital image data in the image reading device 16, and is further binarized using a predetermined threshold value to produce an image as binarized image data. The data is stored in the memory within the reading device 16. A standard butterf 21 as shown in FIG. 3 is stored in advance in the computer 17 as binary image data for comparison. The computer 17/ri calculates the image data based on a predetermined procedure for pattern matching, and selects an area that almost matches the standard pattern 21 from the binarized image (not shown) of the area 20 in FIG. 22 (when a region with a predetermined matching rate or higher is found, it is considered a match).

Figure 4 shows area 2 recognized as pattern matching.
2 schematically shows a binarized image 23 of No. 2. The image recognition mark 7 formed by exposing the semiconductor substrate 4 is almost certainly "
The threshold value is determined so that the black pixel and the seven-node electrode consisting of the aluminum electrode almost certainly become a "white" pixel. Since the image recognition mark 7 is not in a closed ring shape, the match rate between the binarized image data 21 and 26 is not very high;
There should be no practical problem.

In this way, the reference point (for example, the position (X, Y coordinates) of the center point of the region 22) on the bonding stage is accurately determined. Once the reference point is determined, the position of the final node electrode 5 is determined. The bonding position # (the position where the thin lead wire 19 is connected) in the completed node electrode 5 is calculated and determined relatively from the positional relationship from a preset reference point, and the bonding position data is stored in the memory of the computer 17. In addition, the bonding position to the external lead 24 is calculated and determined relative to the determined reference point position, and is stored in the computer 17 as bonding position data.
The accuracy of the bonding position to No. 4 is low due to the influence of the dispersion in the fixing position of the diode chip 11 to the support plate 9. However, since the bonding pad of the external lead 24 has a relatively large area, the diode chip 1
The influence of the positional deviation of 1 is negligible. Of course, the bonding position of the external lead 24 may also be determined by image recognition. Alternatively, the positional deviation of the reference point from the area 20 may be calculated and the bonding position data of the external lead 24 may be corrected. Once the bonding position is determined in this way, the computer 17 issues a command to perform a predetermined wire bonding operation while referring to the bonding position data, and connects one end of the thin lead wire 19 to the anode electrode 5 as shown in FIG. Almost in the center, on the other end? Connect to the bonding pad of the external lead 24.

This embodiment has the following effects.

(1) Since the image recognition mark 7 has an annular planar shape, even if the diode chip 11 is fixed to the support plate 9 with a deviation in the rotational direction, the image recognition mark 7
can be captured as a circular image. Therefore, the problem of inability to perform image recognition due to deviation of the image recognition mark 7 in the rotational direction is solved.

(2) Since the image recognition mark 7 is formed on the anode electrode 5, the diode chip 11 does not become larger due to the provision of the image recognition mark 7.

131 Since the image recognition mark 7 consists of a region where the anode electrode 5 is not partially formed, the image recognition mark 7 can be provided without complicating the manufacturing process〇(4) The anode electrode 5 is used for image recognition It has an inner region and an outer region of the mark 7, the two regions are electrically connected via the residual part 8, and the dynamic region works well as an electrode. Therefore, the actual working area of the anode electrode 5 is large, and good electrical characteristics such as current distribution can be obtained. for example,
Even with a circular image recognition mark, the above fi+ effect can be obtained. However, this is not desirable because the area of the anode electrode 5 decreases and the electrical characteristics deteriorate. Note that even when the remaining portion 8 is not formed, the above two regions are electrically connected via the p shadow region 6.

However, in order to obtain good electrical characteristics, it is desirable to provide the remaining portion 8.

(5) Unnecessary wire bonding is not performed on the support plate 9 where the diode chip 11 is missing.

[Second Example] Next! 71 to 12, the rectifying element and manufacturing method thereof according to the second embodiment of the present invention? explain.

As shown in FIG. 8, the diode chip 7 of this embodiment
1 includes a silicon semiconductor substrate 4 and an anode electrode I&! 5 and a cathode electrode 6. The anode electrode 5 is made of an aluminum electrode formed on almost the entire surface of the semiconductor substrate 4 except for the edge of one main surface. The cathode electrode 6 is formed on the entire surface of the other main surface of the semiconductor substrate 4 except for the edge, and is made of a two-layer electrode made of titanium and nickel. Semiconductor-based 4-piece cathode voltage! It consists of an n shadow area 1, an n shadow area 2, and a p shadow area 3 in order from the 6th side.

The anode electrode 5 has an image recognition label 7 based on the present invention.
is formed. As is clear from FIGS. 7 and 8, the image recognition mark 7 is a non-electronic region where the anode electrode 5 is not partially formed on one main surface of the semiconductor substrate 4. This is the exposed circular part of the surface. In this example, when forming the anode electrode 5 by vacuum deposition, the image recognition mark 7 was formed by using a mask with an RLT constant pattern and not performing vacuum deposition on the area corresponding to the image recognition mark 7. . However, the image recognition mark 7 may be formed by forming the anode electrode 5 on the entire one principal surface of the semiconductor substrate 4 and then partially removing a portion of the anode electrode 5 by etching or the like.

Next, a method of wire bonding using the image recognition mark 7 will be explained.

The automatic wire bonder shown in FIG. 6 is used as in the first embodiment. When performing wire bonding,
The diode chip 11 shown in FIG. 8 is fixed onto the support plate 9 shown in FIG. set in position.

By setting in advance, the TV right camera 3 images an area 20 surrounded by a dotted line in FIG. 7, which reliably includes the reference point to be determined by image recognition. Next, this analog image data is converted from analog to digital by the image reading device 16 and converted to 25
The six-gradation digital image data is combined, further binarized using a predetermined threshold value, and input to the memory in the image reading device 16 as binarized image data.

FIG. 9 schematically shows the binarized image 26 of the region 20. Image recognition mark 7 formed by exposing semiconductor substrate 4
The threshold value is set so that the black J pixel is almost certainly a "white" pixel, and the anode electrode 5 made of an aluminum electrode is almost certainly a "white" pixel. The computer 17 has a first
A standard pattern 21 as shown in FIG. 0 is set in advance as binary image data for comparison. computer 17
calculates the image data based on a predetermined procedure for pattern matching, and finds an area 22 that matches the standard pattern 21 from the binarized image 1 image 26 in FIG. When a region is found where
Y coordinate) is accurately determined.

Once the reference point is determined, the position of the anode electrode 5 is determined, and the bonding position (
The connecting portions of the thin lead wires 19a and 19b) are relatively calculated and determined based on the positional relationship from a preset reference point, and are input into the memory of the computer 17 as bonding position data. Further, the bonding position to the external lead 24 is calculated and determined relatively from the position of the determined reference point, and is stored in the computer 17 as FC boring position data. The accuracy of the bonding position to the external lead 24 is low due to the influence of variations in the position where the diode chip 11 is fixed to the support plate 9. However, since the bonding pad of the external lead 24 has a relatively large area, the position 11 of the diode tip 11 is negligible. Of course, the bonding position of the external lead 24 may also be determined by image recognition. 'Furthermore, the bonding position data of the external lead 24 may be corrected by calculating the deviation of the reference point within the region 2o. When the bonding position is determined in this way, the computer 17tj issues a command to perform a predetermined wire bonding operation while referring to the bonding position data, and as shown in FIG.
One end of a, 19b is connected to the diode chip 11, and the other end is connected to an external lead '24. Two lead wires 19a and 19b are connected to the anode electrode 5 of the diode chip 11. The connecting portions of the thin lead wires 19a and 19b are located on both sides of the image recognition mark R7.

This embodiment has the following effects.

(11 Since the image recognition mark R7 is circular, even if the diode tip 11 is bent in the rotation direction and fixed to the support plate 9, the image recognition mark 7 can be recognized as a circular image. Therefore, the conventional problem of difficulty in recognizing the image GL due to deviation of the diode chip 11 in the rotational direction is solved.

(2) Since the two lead wires #19a and 19b are connected to both sides of the image recognition mark 7 with good positional accuracy, the current distribution in the lead wires AjJ19a and 19b and the diode chip 11 can be obtained satisfactorily. Therefore, the purpose of increasing the allowable current value by reducing the number of thin leads If# to two can be reliably achieved.

(Unnecessary wire bonding is not performed on the support plate 9 where the 31 diode tip 11 is missing.

[Modifications] The present invention is not limited to the above-described embodiments, and, for example, the following modifications are possible.

(1) In the first embodiment, the lead thin a19 may be connected to the @ region outside the image recognition mark 7 of the anode electrode 5. In this case, in order to improve the electrical characteristics, it is preferable to connect two thin lead wires 19 on the left and right sides.

(2) In the first embodiment, the ratio of the image recognition mark 7 to the remaining part 8 can be set arbitrarily, but in order to perform good image recognition, the area of the image recognition mark 7 must be set to the remaining part 8. The area is preferably 1.5 times, preferably 4 times or more, the area of .

+31 The position of the 1IHL image recognition m-sensor 7 is generally provided at the center of the anode electrode 5, but this is not always necessary. In the first embodiment, when the image recognition mark 7 is formed to be biased toward the one side of the anode electrode 5, the wire bonding position is set inside the annular image recognition 11.1ll17 (inside the annular ring). do it.

(41 In the second embodiment, the image recognition mark 7 does not have to have a completely circular planar shape. The image recognition mark 7 shown in FIG. 12 is divided into four parts by the anode electrode 5. Even with such an image recognition target R7,
By setting the matching rate to a low value and performing image recognition R, it is possible to perform wire bonding without any practical problems. Also,
The image recognition mark 7 may be annular, or may not be completely annular.

(511ili image M weave marking 7 may be formed on the upper surface of the anode electrode 5 using a silicon oxide film, polyimide resin, etc.).

〔Effect of the invention〕

As described above, according to the hand conductor element of the present invention, wire bonding using a wire bonder having an image recognition function can be performed satisfactorily.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the relationship between the diode chip of the first embodiment of the present invention and image recognition, and FIG.
3 is a plan view schematically showing a standard pattern, FIG. 4 is a plan view schematically showing an image recognition pattern, and FIG. FIG. 6 is a front view showing the principle of the automatic wire bonder; FIG. 7 is a plan view showing the diode chip of the second embodiment; FIG. FIG. 7 is a cross-sectional view of VIli-11118, FIG. 9 is a plan view schematically showing the image recognition pattern in the second embodiment, and FIG. 10 is a schematic diagram showing the hypothetical pattern of the second embodiment. FIG. 11 is a plan view showing a lead frame equipped with the diode chip shown in FIG. 7, and FIG. 12 is a plan view showing a modification of the image recognition mark. 4... Semiconductor substrate, 5... Anode electrode, 6... Cando electrode, 7... A identification for image recognition, 8... Remaining part, 9... Support plate, 19... Lead thin wire. Agent Nori Takano Figure 3 Figure 4 Figure 5 Figure 1 Figure 2 Figure 6 Figure 9 Figure 10 Figure 11

Claims (1)

[Scope of Claims] [1] A metal electrode for connecting a thin lead wire is formed on one main surface of a semiconductor substrate, and the metal electrode is provided with an image recognition mark, and the image recognition mark is provided with an image recognition mark. is formed into an annular pattern or a substantially annular pattern having a cutout area when viewed from above, and the metal electrode is provided both inside and outside of the image recognition mark when viewed from above. A semiconductor device characterized by: [2] A metal electrode is formed on one main surface of the semiconductor substrate, and the metal electrode is provided with an image recognition mark, and the image recognition mark is located in the center of the metal electrode and has a circular or circular shape. It has a substantially circular or annular planar shape, and is characterized in that one outer portion and the other outer portion of the image recognition mark of the metal electrode are used as connection areas for thin lead wires. semiconductor element.