JP2810261B2 - Method of forming bump electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate in which light detecting elements such as infrared sensors are arranged one-dimensionally or two-dimensionally.
Alternatively, the present invention relates to a method for forming a protruding electrode for forming a signal processing element such as a CCD on a semiconductor substrate or the like in which one-dimensional or two-dimensional array is provided.

[0002]

2. Description of the Related Art Conventionally, this type of bump electrode has been formed by a selective plating method in which electroplating is performed at a predetermined position on a semiconductor substrate to be formed. Alternatively, it is difficult to make the heights and shapes of the formed protruding electrodes uniform evenly due to factors such as variation in the growth of deposited metal particles peculiar to electroplating. If the heights of the protruding electrodes are not uniform, as shown in FIG. 6, the CCD substrate 10 on which the protruding electrodes 40 are formed and the sensor substrate 20
When they are connected by abutting each other, there are cases where the protruding electrodes 40 formed low are not connected to the corresponding output electrodes 21 of the sensor substrate 20, as indicated by the portion indicated by the arrow a.

Therefore, a method has been proposed in which the heights and shapes of the projecting electrodes are made uniform (Japanese Patent Laid-Open No. 64-7638). In this method, the formed protruding electrode 50 is heated and melted, and is spheroidized or hemispherical by its surface tension.
The height and shape of the protruding electrode 50 are made uniform (FIG. 7).

[0004]

However, as described above,
In the method of once melting the formed protruding electrode, the protruding electrode in the molten state lacks stability and is easily spread in the lateral direction, and flows out due to external factors such as vibration,
In some cases, adjacent protruding electrodes contact each other due to rocking, causing a short circuit.

If the pitch between the electrodes forming the protruding electrodes is increased to some extent, the problem that the adjacent protruding electrodes come into contact with each other by swinging in the molten state is reduced, but the density of the substrate is increased. In order to advance the method, there has been a demand for a method of forming a protruding electrode that can be reliably formed even at a narrow pitch.

The present invention has been made in order to solve such a problem, and provides a method of forming a projecting electrode capable of reliably forming projecting electrodes having a uniform height and shape even at a narrow pitch. The purpose is to:

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned object, and its gist is to form a base metal film for a plating electrode on a semiconductor substrate such as a photodetection substrate or a signal processing substrate. A step of selectively forming a resist film on the surface of the formed base metal film, exposing regions where a plurality of projected electrodes are to be formed, and performing electroplating on the surface of the base metal film on which the resist film is formed, Depositing the electrode material of the projection electrode in the region where each projection electrode is to be formed, and depositing the electrode material deposited in the region where each projection electrode is to be formed with the resist film surrounding the electrode material in the formation region. And a step of heating and melting the partition electrode as a partition wall.

[0008]

After depositing the electrode material in the area where each protruding electrode is to be formed, the deposited electrode material is heated and melted in the area where the projection electrode is to be formed. The area where the electrode material is to be formed is surrounded by a resist film. It is formed in a state where it is set. Therefore, the resist film forming the region where the projecting electrode is to be formed functions as a partition wall for accommodating the electrode material in a molten state, and also functions as a shaping type for shaping the deposited electrode material. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for forming a bump electrode according to the present invention will be described below in the order of steps with reference to the accompanying drawings.

As shown in FIG. 1, a plurality of input electrodes 12 are provided on the surface of a CCD substrate 10 as a signal processing substrate, and a contact hole electrode made of an Al film for forming a protruding electrode is provided above the input electrodes 12. 13 are formed. Although omitted in the figure, since a large number of signal line electrodes are formed on the surface of the CCD substrate 10, a passivation film 14 such as an insulating film is formed to protect the surface of the substrate.

The CCD substrate 10 formed as described above
Then, a Ti film 15 and an Au film 16 are sequentially deposited on the entire surface to form a base metal film (FIG. 2). The Ti film 15 is a barrier metal, and the Au film 16 is a plating electrode.

Next, a resist film 17 is formed on the Au film 16 surface.
(See FIG. 3) to expose a region where the bump electrode is to be formed on the surface of the Au film 16.

Next, using the formed resist film 17 as a protective film for electroplating, an electrode material 11 ′ made of a low-melting metal, for example, In, is deposited in a region where a bump electrode is to be formed by a selective plating method (FIG. 3). (A)). Specifically, the CCD substrate 10 is immersed in an In plating solution, and the Au film 16 is used as an electrode to perform plating at room temperature with a predetermined current value for several tens minutes. Thereby, the deposited metal material is several tens μm.
m. At this time, even if the plating current is controlled to be constant, the height and shape of the electrode material 11 ′ are
They are not uniform due to factors such as variations in the growth of deposited metal particles specific to electroplating.

Next, the deposited electrode material 11 'is heated to the melting point of In, and the electrode material 11' is melted in the region where each protruding electrode is to be formed (FIG. 3B). Since the region where each projection electrode is to be formed is formed so as to be surrounded by the resist film 17, the resist film 17 which forms each formation region has the electrode material 11 ′ in a molten state in this region. In addition to functioning as a partition wall for housing, it also functions as a shaping mold for shaping the deposited electrode material 11 ′.

Next, the molten electrode material 11 'is lowered to a temperature lower than the melting point and solidified. Next, after removing the resist film 17 functioning as a shaping mold, the shaped electrode material is removed.
Using the 11 ′ as a mask, the exposed Au film 16 and the Ti film 15 immediately below the exposed Au film 16 are sequentially etched and removed.
Is completed (FIG. 4). Thereby, the protruding electrode 11 having a uniform height and shape can be obtained.

After the protruding electrodes 11 are formed on the CCD substrate 10 as described above, as shown in FIG. 5, the CCD substrate 10 is connected to the sensor substrate 20 as a light detection substrate, and the semiconductor device 1 is mounted. To manufacture. When connecting the two substrates, first, each output electrode 21 on the lower surface of the sensor substrate 20 is connected to C
The alignment with the respective protruding electrodes 11 on the CD substrate 10 is performed, and then the two substrates 10 and 20 are connected to each other by abutting each other. At this time, since the heights of the projecting electrodes 11 are all uniform, the projecting electrodes 11 are all connected to the output electrodes 21 of the sensor substrate 20, and the CCD substrate 10 and the elements of the sensor substrate 20 are securely connected. Can be connected.

In this embodiment, the example in which the protruding electrode 11 is formed on the CCD substrate 10 has been described. However, the protruding electrode 11 can be formed on the sensor substrate 20 side, and can be formed on another semiconductor substrate. It is possible.

[0018]

As described above, according to the method for forming a bump electrode according to the present invention, a plurality of regions where bump electrodes are to be formed are formed on the surface of the underlying metal film by a resist film. Then, a method was employed in which after the electrode material was deposited, the deposited electrode material was heated and melted in each region to be formed.

Therefore, the resist film forming each of the regions to be formed functions not only as a partition wall for accommodating the molten electrode material but also as a shaping type for shaping the deposited electrode material. It is possible to prevent the electrode material in the molten state from flowing around or swinging to contact adjacent electrode materials, and to reliably form a projection electrode having a uniform height and shape even at a narrow pitch. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a CCD substrate.

FIG. 2 is a partial cross-sectional view showing a state where a base metal film is formed on a CCD substrate.

FIG. 3A is a partial cross-sectional view of a CCD substrate showing a state where an electrode material is deposited on a region where a protruding electrode is to be formed by electroplating, and FIG. 3B is a diagram showing a state in which the deposited electrode material is heated. FIG. 3 is a partial cross-sectional view of the CCD substrate in a molten state.

FIG. 4 is a partial cross-sectional view showing a CCD substrate on which protruding electrodes are formed.

FIG. 5 is a partial cross-sectional view showing a semiconductor device in which a CCD substrate and a sensor substrate are connected in abutting relation.

FIG. 6 is a partial sectional view showing a conventional semiconductor device.

FIG. 7 is a partial cross-sectional view of a semiconductor substrate showing a conventional method for forming a bump electrode.

[Explanation of symbols]

1 ... Semiconductor device, 10 ... CCD board (signal processing board),
11: projecting electrode, 11 ': electrode material, 16: Au film (base metal film), 17: resist film, 20: sensor substrate (light detection substrate).

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-59945 (JP, A) JP-A-1-122141 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) H01L 21/60 H01L 27/146

Claims (3)

(57) [Claims] 1. A step of forming a base metal film for a plating electrode on a semiconductor substrate, and selectively forming a resist film on a surface of the formed base metal film to expose regions where a plurality of bump electrodes are to be formed. A step of: electroplating the surface of the base metal film on which the resist film is formed, and depositing an electrode material of the bump electrode in the area where the bump electrode is to be formed; And fusing the electrode material deposited in the region to be formed with the resist film surrounding the electrode material as a partition wall in the formation scheduled region. 2. The semiconductor substrate according to claim 1, wherein said semiconductor substrate has a detection unit for converting an optical signal into an electric signal, and said electric signal obtained by said detection unit.
2. The method according to claim 1, wherein the substrate comprises a plurality of output electrodes for extracting light. 3. The signal processing substrate according to claim 1, wherein the semiconductor substrate has a plurality of input electrodes and includes a processing circuit for processing an electric signal input to the input electrodes. Forming method of the bump electrode.