JP2581299B2 - Method for manufacturing semiconductor device having bump electrode - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor device having a protruding bump electrode disposed on a semiconductor substrate.

[Prior Art] For example, a hybrid infrared sensor includes a semiconductor chip for photoelectric conversion in which an infrared detecting element is provided on a semiconductor substrate, and a silicon IC semiconductor chip on which a signal processing circuit for processing an output signal is formed. Manufactured by combining. When such a semiconductor chip is electrically and mechanically connected, generally, a bump-shaped bump electrode made of a soft metal such as indium is formed on both semiconductor chips, and the bump electrodes are aligned with each other. Thermocompression bonding.

FIG. 3 is a sectional view showing a conventional method of manufacturing a semiconductor device having bump electrodes in the order of steps.

First, as shown in FIG. 3A, after an insulating film 27 is formed on a semiconductor substrate 21, an opening is provided in the insulating film 27 in a region 22 where a bump electrode is to be formed. Next, a high-concentration n-type layer 28 is formed on the surface of the semiconductor substrate 21 in the opening, and an ohmic electrode is formed on the high-concentration n-type layer 28 and the insulating film 27 in the vicinity thereof.
23 is selectively formed.

Next, as shown in FIG. 3 (b), a plating base metal film 24 is deposited on the entire surface. The plating base metal film 24 is used not only as a plating base but also as a wiring for supplying a plating current.

Next, as shown in FIG. 3 (c), a photoresist film 25 having an opening in the region 22 where a bump electrode is to be formed is formed on the metal substrate 24 for plating. Then, plating metal film
The bump electrode 26 is selectively formed on the plating base metal film 24 in the bump electrode formation region 22 by using the photoresist film 25 as a mask and the photoresist film 25 as a mask.

Next, as shown in FIG.
Remove 25.

Thereafter, as shown in FIG. 3 (e), after removing the photoresist film 25, the plating underlying metal film 24 is selectively removed by etching using the bump electrode 26 as a mask to electrically connect the elements. By separating, a semiconductor device having a bump electrode can be manufactured.

According to the method of manufacturing a semiconductor device having such a bump electrode, the bump electrode 26 having a thickness of 5 μm or more is required.
Can be easily formed.

[Problems to be Solved by the Invention] However, the above-described conventional method for manufacturing a semiconductor device having a bump electrode has the following problems in the step of removing the plating base metal film 24. That is,
When the base metal film 24 is etched using the bump electrode 26 as a mask, the bump electrode 26 itself is slightly etched. In addition, the plating base metal film 24 immediately below the bump electrode 26 is eroded from the periphery thereof, and the connection strength of the bump electrode 26 is reduced. Further, the insulating film 27 is also slightly etched, and the element characteristics of the semiconductor device deteriorate. As a result, there is a problem that the yield rate and reliability of the semiconductor device having the bump electrode are reduced.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method of manufacturing a semiconductor device having a bump electrode, which can manufacture a semiconductor device having a highly reliable bump electrode at a high yield rate. Aim.

[Means for Solving the Problems] A method of manufacturing a semiconductor device having a bump electrode according to the present invention is directed to a method of manufacturing a semiconductor device having an integrated circuit formed on a semiconductor substrate having an opening in a region including a region where a bump electrode is to be formed. Forming a photoresist film, and dissolving and removing the first photoresist film after depositing a metal film for plating underlayer on the entire surface, thereby forming the metal film on the first photoresist film. Removing, a step of forming a second photoresist film having an opening in the area where the bump electrode is to be formed on the semiconductor substrate, and driving the integrated circuit to remain in the area where the bump electrode is to be formed Supplying a plating current to the metal film to form a bump electrode on the metal film.

[Operation] In the present invention, a first photoresist film having an opening in a region including a region where a bump electrode is to be formed is formed on a semiconductor substrate, and a metal film for plating underlayer is coated on the entire surface, so-called, By dissolving and removing the first photoresist film by a lift-off method, the metal film on the first photoresist film is removed. This allows
The metal film for plating underlayer is left on the semiconductor substrate in the region where the bump electrode is to be formed. Then, after forming a second photoresist film having an opening in the bump electrode formation planned region on the semiconductor substrate, the integrated circuit is driven to plate the metal film remaining in the bump electrode formation region. Supply current. Thereby, a bump electrode can be formed on the metal film in the opening of the second photoresist film.

According to the present invention, an integrated circuit on a semiconductor substrate is driven to supply a plating current to a metal film used as a base for plating. Therefore, the metal films can be formed separately from each other in advance.
For this reason, after the bump electrode is formed on the metal by plating using the metal film as a cathode, there is no need to etch an unnecessary metal film for plating base unlike the conventional case. Therefore, the conventional problem associated with the etching of the plating base metal film, that is, the bump electrode is etched when the unnecessary plating base metal film is removed, or the plating base metal film immediately below the bump electrode is eroded. As a result, it is possible to prevent the connection strength of the bump electrode from being lowered and prevent the insulating film from being etched, and to manufacture a semiconductor device having a highly reliable bump electrode at a high yield rate.

Further, in the present invention, the time for supplying the plating current to the plating base metal film can be appropriately changed according to the driving method of the integrated circuit. Therefore, it is possible to form the bump electrode by a so-called pulse plating method. it can. According to this pulse plating method, the bump electrode can be made finer in its particle, its defect density can be reduced, and contamination of impurities can be reduced. Thereby, the reliability of the semiconductor device having the bump electrode can be further improved.

Example Next, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a method of manufacturing a semiconductor device having a bump electrode according to a first embodiment of the present invention in the order of steps.
The figure is a circuit diagram showing an example of a signal processing circuit formed on the semiconductor substrate. In this embodiment, indium is used as a constituent metal of the bump electrode.

First, as shown in FIG. 1 (a), after an insulating film 5 is formed on a semiconductor substrate 1 made of p-type silicon, an insulating film 5 in a region 2 where a bump electrode is to be formed and a region where a plating current supply electrode is to be formed. Is provided with an opening. Next, after the high concentration n-type layer 4 is formed on the surface of the semiconductor substrate 1 in the bump electrode formation scheduled area 2, aluminum or the like is respectively formed on the bump electrode formation scheduled area 2 and the plating current supply electrode formation scheduled area on the semiconductor substrate 1. Signal input electrode 11 consisting of plating current supply electrode 15
Is patterned. Next, a photoresist film 3 having an opening in the region 2 where the bump electrode is to be formed and the region where the plating current supply electrode 15 is to be formed is patterned on the insulating film 5.

A signal supplied from a photoelectric conversion semiconductor chip (not shown) is input to the signal input electrode 11, and a predetermined signal processing circuit including the signal input electrode 11 is provided on the semiconductor substrate 1. A plurality of signal processing semiconductor chips are formed, and a signal from the photoelectric conversion semiconductor chip is processed in the signal processing circuit.

The above-described signal processing circuit is configured, for example, as shown in FIG. That is, a plurality of infrared sensors 20 respectively connected to the signal input electrodes 11 are arranged in a matrix, a plurality of column lines are connected to the decoder 16, and a plurality of row lines are connected to the shift register 17. The decoder 16 and the shift register 17 are each provided with a plurality of signal processing circuit driving electrodes 12.
, And a cell in a predetermined column and row is selected from a plurality of cell groups according to the pulse signal. The signal input electrode 11 is connected to the cell and the infrared sensor 20.
And is provided between them. The capacitor 18 is provided in each row line connecting the shift register 17 and the cell group, and accumulates electric charge in accordance with the amount of infrared light incident on the infrared sensor 20. The signal output amplifier 19 outputs a signal to the outside by using the charge stored in the capacitor 18 as a voltage. The reset voltage input terminal 14 is connected to the signal input electrode 11 via the capacitor 18 and the cell. This reset voltage input terminal 14 is used as the plating supply electrode 15 in FIG.

Next, as shown in FIG. 1B, a metal film 6 is deposited on the entire surface. This metal film 6 is used for the signal input electrode 11 and the insulating film 5.
In this embodiment, for example, a chromium film, a titanium film, or a laminated film of such a film and a copper film or a gold film can be used. The metal film 6
Since the photoresist film 3 is provided, a step is generated between the portion on the photoresist film and other portions, and the step is separated by the step.

Next, as shown in FIG. 1 (c), by dissolving and removing the photoresist film 3 by a so-called lift-off method, the metal film 6 formed on the photoresist film 3 is removed.
Is removed. Thus, the plating base metal film 7 is patterned on the signal input electrode 11 in the bump electrode formation planned area 2, and the electrode terminals 13 are patterned on the plating current supply electrode 15 and the insulating film 5 in the vicinity thereof.

Next, as shown in FIG. 1D, a photoresist film 8 having an opening in the bump electrode formation planned area 2 (on the plating base metal film 7) is formed on the insulating film 5. Next, by inputting a predetermined pulse signal to the signal processing circuit driving electrode 12 shown in FIG. 2, the decoder 16 selects all the columns, and the shift register 17 inputs a high-level data pulse signal while inputting a clock signal. Input a pulse signal and select all rows. Thereby, all the signal input terminals 11 are turned on. Next, a plating current is supplied to all the plating base metal films 7 via the electrode terminals 13 and the plating current supply electrode 15. Then, indium is plated and grown using the plating base metal film 7 as a cathode and the photoresist film 8 as a mask, and a bump electrode (indium bump) 9 made of indium is formed on the plating base metal film 7.

Thereafter, as shown in FIG. 1E, by removing the photoresist film 8, a semiconductor device having a bump electrode can be manufactured.

In this embodiment, unlike the conventional method, there is no step of etching and removing the plating base metal film 7 after plating. That is, in the conventional method, the plating base metal film is formed as a common electrode, that is, a continuous film, in order to supply a plating current to the plating base metal film in all the bump electrode formation regions arranged on the semiconductor substrate. For this reason, after the plating process, it is necessary to pattern the underlying metal film by etching. However, in the method of the present embodiment, each plating base metal film 7 is formed by a lift-off method.
Are formed separately, and a plating current is supplied to each plating base metal film 7 using an integrated circuit formed on the semiconductor substrate. For this reason, according to the present embodiment, the bump electrode is etched when the unnecessary plating base metal film is removed unlike the related art, or the plating base metal film immediately below the bump electrode is eroded to connect the bump electrode. It is possible to prevent the strength from decreasing and the insulating film from being etched. Therefore,
A semiconductor device having a highly reliable bump electrode can be manufactured at a high yield rate.

Further, in the present embodiment, the driving method of the signal processing circuit is changed by, for example, selecting the decoder 16 and the shift register 17 one by one and one row, respectively, so that the electrical connection state of the plating base metal film 7 is changed. Can be intermittent rather than continuous. Therefore, the time for supplying the plating current to the plating base metal film 7 can be appropriately changed, so that the bump electrodes 9 can be formed by a so-called pulse plating method. According to this pulse plating method, the bump electrode 9 can have its particles finer, its defect density can be reduced, and its contamination with impurities can be reduced. Thereby, the reliability of the semiconductor device having the bump electrode can be further improved.

In the above embodiment, the semiconductor substrate 1 is made of silicon, and the bump electrode 9 is made of indium. However, in the present invention, the semiconductor substrate is made of gallium arsenide or A normal semiconductor substrate made of indium antimony or the like can be used, and a soft metal such as antimony, bismuth, lead, tin and zinc, or a laminate of these with copper or gold can be used as the bump electrode.

[Effects of the Invention] As described above, according to the present invention, an integrated circuit of a semiconductor substrate is driven to supply a plating current to a metal film for plating underlayer. Can be. Therefore, it is not necessary to etch the metal film after forming a bump electrode on the metal film by plating using the metal film as a cathode. Therefore, the conventional problems associated with the etching of the plating base metal film can be solved, and a semiconductor device having a highly reliable bump electrode can be manufactured at a high yield rate.

Further, in the present invention, the time for supplying the plating current to the metal film for the base of plating can be appropriately changed according to the driving method of the integrated circuit. Therefore, the bump electrode is formed by a so-called pulse plating method. Accordingly, there is an effect that the reliability of the semiconductor device having the bump electrode can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method of manufacturing a semiconductor device having bump electrodes according to a first embodiment of the present invention in the order of steps, and FIG. 2 is a circuit diagram showing an example of a signal processing circuit formed on the semiconductor substrate. FIG. 3 is a sectional view showing a conventional method for manufacturing a semiconductor device having bump electrodes in the order of steps. 1,21; semiconductor substrate, 2,22; bump electrode formation planned area, 3,8,
25; photoresist film, 4, 28; high-concentration n-type layer, 5, 27; insulating film, 6; metal film, 7, 24; plating base metal film, 9, 26; bump electrode, 11; signal input electrode, 12; signal processing circuit driving electrode, 1
3; electrode terminal, 14; reset electrode input terminal, 15; plating current supply electrode, 16; decoder, 17; shift register, 18; capacitor, 19; signal output amplifier, 20; infrared sensor, 23;
Ohmic electrode

Claims (2)

(57) [Claims] A step of forming a first photoresist film having an opening in a region including a region where a bump electrode is to be formed on a semiconductor substrate on which an integrated circuit is formed; Removing the metal film on the first photoresist film by dissolving and removing the first photoresist film after the deposition, and opening the bump electrode formation region on the semiconductor substrate. Forming a second photoresist film having a portion, and supplying a plating current to the metal film remaining in the bump electrode formation scheduled region by driving the integrated circuit, thereby forming a bump electrode on the metal film. A method of manufacturing a semiconductor device having a bump electrode. 2. The method according to claim 1, wherein the bump electrodes are formed by a pulse plating method.