JPH0719892B2 - Method for sealing semiconductor light receiving device - Google Patents

Description

The present invention relates to a method for sealing a semiconductor light receiving device, and more particularly to a semiconductor light receiving device having a semiconductor light receiving element, which is sealed by resin sealing. Regarding the method.

[Prior Art] One of sealing methods for a semiconductor light receiving device is a so-called clear mold package in which a semiconductor light receiving element or the like is sealed with a light-transmitting resin.

FIG. 7 is a cross-sectional view showing an example of a semiconductor light receiving device sealed by a clear mold package.

In the figure, 1 is a light-transmitting resin which is a sealing body, 2 is a semiconductor chip which is a semiconductor light receiving element, 3a, 3b and 3c are lead frames, and 4 is a bonding wire which connects the semiconductor chip 2 and the lead frames 3a and 3c. Is.

[Problems to be Solved by the Invention] The semiconductor light receiving device has advantages such as excellent mass productivity, cost reduction, and size reduction, since many elements can be resin-molded at one time. However, it had the following problems.

(1) Stress is generated due to the difference in expansion coefficient between the semiconductor chip 2 and the light-transmissive resin 1 to change the characteristics, and
In an extreme case, the semiconductor chip 2 may be cracked or the wiring may be deformed.

(2) Defects on the surface of the light-transmissive resin, and foreign light existing on the surface and the inner surface of the light-transmitting resin is blocked or diffusely reflected to deteriorate the characteristics of the semiconductor light receiving device.

(3) Reflection of light at the interface between the light transmissive resin and the outside air affects the characteristics of the semiconductor light receiving element. Incident light is reduced by reflection, and light reflected on the surface of the semiconductor chip is reflected again at the interface between the light transmissive resin and the outside air, which changes the output characteristics of the semiconductor light receiving element.

(4) The spectral characteristic of the transparent resin affects the spectral sensitivity characteristic of the entire semiconductor light receiving device. For example, ultraviolet rays are blocked by a resin, and it is difficult to use a clear mold package as an ultraviolet ray sensor.

(5) The entire clear mold package is transparent,
It is easily affected by the surrounding light such as reflected light from the bonding wire.

Among the above problems, particularly (2), (3), and (5) have been great obstacles in applications such as an autofocus mechanism that requires a highly sensitive and highly accurate semiconductor light receiving element.

In view of the above-mentioned problems, an object of the present invention is to provide a sealing method which is used in manufacturing a semiconductor light-receiving device with improved yield, low cost, high accuracy, high sensitivity, and high reliability. is there.

[Means for Solving Problems] In the method for sealing a semiconductor light receiving device which has a semiconductor light receiving element and is sealed by resin sealing, at least the light receiving region of the semiconductor light receiving element is provided. This is achieved by the method for sealing a semiconductor light receiving device of the present invention, which is characterized in that the thickness of the sealing body is reduced and the thin sealing body portion is removed in a later step.

[Operation] According to the present invention, at least the thickness of the sealing body on the light receiving region of the semiconductor light receiving element is reduced, and the thin sealing body portion is removed in a later step, so that the sealing body portion is not removed. In this process, it is possible to prevent the deterioration of the semiconductor light receiving element, prevent the adhesion of foreign matter such as scratches and dust, and remove the thin encapsulant part without impairing the resin thickness of other parts. Since it is possible to form the hollow area of the sealing body with high accuracy, the sealing step only changes the removal step of the thin sealing body part, and the conventional sealing step is significantly changed. It is possible to perform the sealing without doing so.

EXAMPLES Examples of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a semiconductor light receiving device sealed by the present invention. The same members as those in FIG. 7 are designated by the same reference numerals and the description thereof is omitted.

In the figure, 5 is a hollow region, 6 is a light receiving region on the semiconductor chip 2 which is a semiconductor light receiving element, 7 is a light transmissive member, and 10 is a resin which is a sealing body. As will be described later, the resin 10 does not have to be a light transmissive resin as shown in FIG. 7, and may be a resin having no light transmissive property.

A feature of this semiconductor light receiving device is that there is no resin on the light receiving region 6 of the semiconductor light receiving element and its vicinity, and it is a hollow region.

That is, in the semiconductor light receiving device, the hollow region 5 is provided, and the contact area between the semiconductor chip 2 and the resin 10 is reduced, so that the stress is reduced (the problem (1) is reduced) and the resin is reduced.
Since part of 10 is removed and the path of incident light becomes a hollow region, it is not necessary to consider scratches on the resin surface, foreign matter such as dust on the resin surface and inside, and the spectral transmission characteristics of the resin. Since the path is provided, it is not always necessary to use a light-transmissive resin, and as a result, it is not necessary to consider the wraparound of light from the surroundings due to light reflection or the like (problem (2), problem (4), Since the interface between the light receiving region 6 on the semiconductor chip 2 and the resin 10 is eliminated (the problem (5) is solved), it is not necessary to consider the reflected light from the interface (the solution to the problem (3)). It has the advantages of improved yield in the manufacturing process, simplified handling, and high sensitivity, high accuracy, and high reliability.

In general, a semiconductor element is often wired by a substance mainly containing aluminum, and therefore a pad portion on the semiconductor element to which a bonding wire is connected is also often made of aluminum. In this case, moisture resistance generally becomes a problem due to migration, insulation and the like, and it is desirable that the resin is sealed with a resin or the like.

In the above semiconductor light receiving device, as shown in FIG.
Since the wiring portion such as the pad portion is sealed with the resin, the problems such as the moisture resistance are alleviated. Since the resin is removed from the light receiving region 6 and its vicinity, there is a concern that reliability problems such as moisture resistance may occur. However, light transmission having a spectral transmittance according to the spectral characteristics of the semiconductor light receiving device may occur. The problem is solved by fixing the elastic member to the resin 10 so as to cover the hollow region 5 and blocking it from the outside air. Further, if the semiconductor light receiving element is coated with a passivation film such as silicon nitride to make the element itself highly reliable,
Even if the package structure according to the present invention is used, reliability as a semiconductor light receiving device is not lost.

In the above embodiments, the semiconductor light receiving element may be integrated into an IC and mounted on one chip together with other signal processing circuits.

As a method of resin sealing, a hollow plastic package is prepared in advance, a semiconductor light receiving element or the like is inserted and fixed therein, wiring is performed thereafter, and finally, a resin is covered with a light transmissive member. Although there is a sealing method, the semiconductor light receiving device has various advantages unlike this sealing method. For example, since the wiring portion such as the pad portion is sealed with resin, This has the advantage that the reliability of the part is maintained.

Hereinafter, the method for sealing the semiconductor light receiving device of the present invention will be described.

2 to 6 are process drawings for explaining the method for sealing the semiconductor light receiving device of the present invention. The same members as those shown in FIGS. 1 and 7 are designated by the same reference numerals and the description thereof is omitted.

First, as shown in FIG. 2, the semiconductor chip 2, which is a semiconductor light receiving element, is bonded and fixed onto the lead frame 3b by a conductive adhesive material 8 such as Ag paste.

Next, as shown in FIG. 3, a thin bonding wire 4
Is bonded to connect the pad portions on the semiconductor chip 2 to the lead frames 3a and 3c.

Next, as shown in FIG. 4, resin sealing is performed. At this time, for example, by changing the shape of the mold, the thickness is controlled so that at least the resin 10 in the light receiving region 6 and its vicinity can be removed in a later step, and the thin resin portion 9 is formed. The thickness of the thin resin portion 9 can be controlled by using a mold and taking into consideration the variation in the thickness of the semiconductor chip 2 which is a semiconductor light receiving element.

For example, assuming that the variation of the thickness of the semiconductor chip 2 is ± 25 μm and the minimum value of the thickness of the thin resin portion 9 is set to 20 μm, the resin having a thickness of 20 μm to 70 μm is used as a light receiving area and It is possible to leave it in the vicinity. A characteristic part of the method for sealing a semiconductor light receiving element of the present invention is to form a hollow region by removing the above-described light receiving region and a thin resin portion in the vicinity thereof in a later step. It has the following advantages:

(1) It is possible to prevent the die from directly contacting the semiconductor chip during the sealing and breaking the semiconductor chip.

(2) The semiconductor chip is protected as a protective film until the resin in the light receiving region and its vicinity is removed later.

Next, as shown in FIG. 5, after the resin sealing is completed, deburring, plating, and lead cutting are performed. These steps are the same as the conventional steps.

Next, as shown in FIG. 6, the resin in the light receiving region 6 and its vicinity is removed.

In the resin removal, it is required that the lead frame is not affected by corrosion or the like, and that the exposed semiconductor light receiving element, the semiconductor chip, is not affected at all. One of the resin removing methods that satisfies such conditions is a method of removing the resin by dissolution. For example, when the sealing resin is an acid anhydride-cured glycidyl ether type resin, it can be dissolved by a solution mainly containing diethylene glycol (HOCH ₂ CH ₂ ) ₂ O. Diethylene glycol (HOCH ₂ CH ₂ ) ₂ O in which potassium hydroxide (KOH) is dissolved does not corrode the lead frame as long as potassium hydroxide is not liberated by hydrolysis due to the inclusion of water. If the semiconductor light receiving element is passivated with, for example, silicon nitride, the possibility that the solution will affect the element is low.

Since the resin on the light receiving area and its vicinity is remarkably thinner than the other portions, it is easy to dissolve the resin in the thin portions without impairing the thickness of the resin in the other portions.

Finally, the light transmissive member is adhered to produce the plastic package shown in FIG.

As described above, the method for sealing the semiconductor light receiving device of the present invention,
The sealing can be performed only by adding the step of melting the resin, and the other conventional steps are not changed.

[Effects of the Invention] As described in detail above, according to the method for manufacturing the semiconductor light receiving device of the present invention, at least the thickness of the sealing body on the light receiving region of the semiconductor light receiving element is made thin, and this thin film is formed in the subsequent step. By removing the sealing body portion, it is possible to prevent deterioration of the semiconductor light receiving element in the process before the removal of the sealing body portion, and to prevent foreign matter such as scratches and dust from adhering. Furthermore, since the thin encapsulant portion can be removed without impairing the thickness of the resin in other portions, the hollow region of the encapsulant can be formed with high accuracy, and the encapsulation process can reduce the thickness. Only the step of removing the thin sealing body portion is increased, and the sealing can be performed without significantly changing the conventional sealing step. As a result, it is possible to provide a semiconductor light receiving device that improves the yield in the manufacturing process, is easy to handle, is low in cost, has high sensitivity, high accuracy, and is highly reliable.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor light receiving device sealed by the present invention. 2 to 6 are process drawings for explaining the method for sealing the semiconductor light receiving device of the present invention. FIG. 7 is a cross-sectional view showing an example of a semiconductor light receiving device sealed by a clear mold package. 1 ... Light-transmitting resin 2 ... Semiconductor chips 3a, 3b, 3c ... Lead frame 4 ... Bonding wire 5 ... Hollow region 6 ... Light receiving region 7 ... Light transmitting member 8 ... Conductive adhesive 9 …… Thin resin part 10 …… Resin

Claims (1)

[Claims] 1. A method for sealing a semiconductor light receiving device having a semiconductor light receiving element, which is sealed by resin sealing, wherein at least a thickness of a sealing body on a light receiving region of the semiconductor light receiving element is reduced, A method for sealing a semiconductor light receiving device, characterized in that the thin sealing body portion is removed in a subsequent step.