JPH0714842A - Inspection of bump and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to measure the volume of each bump of a plurality of bumps with good accuracy and easily. CONSTITUTION:A method of inspecting bumps is a method of controlling the volume of each bump of a plurality of pieces of the bumps 2, which are dispersedly arranged on one substrate 1, for example, a method wherein the surface, on which a plurality of bumps 2 consisting of a Pb/Sn alloy, an In/Pb alloy or the like are provided, of a substrate 1 is pressed 4 by a flat plate parallel to the substrate 1 in a state that the plurality of the bumps 2 are heated 5 at normal temperature or a temperature less than the melting point of a substrate composing the bumps, for example, to crush the plurality of the bumps 2 to a uniform height and thereafter, the bump arrangement surface of the substrate 1 is observed by a microscope from directly over. The method is constituted so as to have a process in which an image observed by the microscope is binarized to distinguish the part 102 of each bump 2 of the plurality of the bumps from a part 101 other than the bump and the volume of each bump 2 is measured by calculating individually the number of pixels of the part 102 of each bump 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bump inspection method and a bump inspection method for controlling a volume distribution of bumps (bump electrodes) arranged in a distributed manner on a substrate to a predetermined width. And a method for manufacturing a semiconductor device including the above.

In recent years, LSIs have been highly integrated and become faster,
Corresponding to the LSI chip mounting technology, a method capable of high-density mounting such as flip chip and MCM (Multi Chip Module) is required. Indispensable for these high-density mounting is a bump using a soft metal having a low melting point, such as a lead (Pb) / tin (Sn) alloy or an indium (In) / Pb alloy. These bumps are heated and melted to a temperature equal to or higher than the melting point in a non-oxidizing atmosphere and are connected to a pad such as a wiring board serving as a receiver. Therefore, in order to secure the reliability of the connection, it is necessary to make the volume of the bumps arranged on one substrate within a certain range, and to measure the volume of the bumps easily and with high accuracy in a short time. There is a demand for a bump inspection method capable of performing the above.

[0003]

2. Description of the Related Art In a conventional bump inspection method for controlling the volume of a bump, only the height of the bump is measured by a step measuring device or an auto-focusing device.

However, even if the bumps have the same height, some bumps have different volumes due to the difference in the spread dimension, and therefore the volume control of the bumps becomes insufficient only by measuring the height.
Therefore, when the volume of the bump is managed by the conventional bump inspection method that measures only the height of the bump, the width of the variation (distribution) of the volume of the bump becomes large, and for example, a semiconductor chip is mounted on the chip. When it is welded and connected to a pad such as a wiring board through a bump of the Pb alloy or the like,
The reliability of the connection and the yield are deteriorated because the stress resistance strength of the connection is lowered due to the insufficient amount of the Pb alloy or the like of the bump material, and the short circuit between the adjacent electrodes is caused due to the excessive amount of the bump material. There was a problem of doing.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention provides a bump inspection method and a semiconductor device manufacturing method including the bump inspection method capable of accurately and easily measuring the volume of the bump. An object of the present invention is to improve the management accuracy of the volume of bumps and improve the manufacturing yield and reliability of LSIs and the like in which semiconductor chips and the like are mounted at high density via bumps.

[0006]

A solution to the above problem is a bump inspection method for controlling the volume of a plurality of bumps dispersedly arranged on one substrate. For example, a Pb / Sn alloy or an In / Pb alloy is used. The surface of the substrate having a plurality of bumps made of, for example, is a flat plate parallel to the substrate, and the plurality of bumps are pressed at a normal temperature or a temperature lower than the melting point of the bump material to press the plurality of bumps uniformly. After crushing to height,
The bump placement surface of the substrate is observed from directly above, and the observed image is binarized, for example, to distinguish the bump portion of each of the plurality of bumps from the portion other than the bump, and determine the number of pixels of each bump portion. A bump inspection method according to the present invention, in which the area occupied by the bumps is measured by individually counting, and the volume of the bumps is inspected based on the area occupied, or a method for manufacturing a semiconductor device having bumps for external connection And forming an insulating film on a semiconductor substrate on which a plurality of pads for arranging bumps are formed, and forming openings for individually exposing the plurality of pads in the insulating film, This is achieved by the method for manufacturing a semiconductor device according to the present invention, which includes the step of inspecting the volume of each bump by the above-mentioned bump inspection method after forming the bumps individually connected to the respective pads.

[0007]

The principle of the present invention will be described below. FIG. 1 is a diagram illustrating the principle of the present invention, and (a) to (c) are schematic diagrams of each step.

It is very difficult to directly measure the volume of the bump. Therefore, in the present invention, as shown in FIG.
On the semiconductor chip 1 which is the substrate on which the bumps 2 are arranged, for example, a flat plate parallel to the semiconductor chip 1, that is, a parallel plate 3
1b, the parallel plate 3 presses the bumps 2 on the bumps 2 with a force 4 perpendicular to the semiconductor chip 1 to force the height h'of the bumps 2 to a constant height. Will be aligned with. At this time, it is desirable to heat the bumps 2 to a temperature close to the melting point by the substrate heating 5 to soften the bumps so as not to damage the underlying semiconductor chip 1 depending on the type of bump material.

By keeping the height constant in this way,
The three-dimensional difference in volume can be accurately replaced with the two-dimensional difference in plane area. Therefore, the distribution of the bump volume can be known with high accuracy by optically measuring the plane area of the bump using a microscope or the like.

In the method of the present invention, the plane area of the crushed bump is measured by binarizing an optical observation image from directly above the bump by image processing as shown in FIG. 1 (c). The portion 102 of the bump 2 and the other portion 101 are distinguished from each other, and a method of counting the number of pixels of the portion 2 of the bump is used so that it can be performed easily and at high speed.

As described above, according to the present invention, it is possible to easily and accurately manage the volume distribution of the plurality of bumps dispersedly arranged on the substrate. Therefore, by applying the semiconductor device manufacturing method of the present invention including the bump inspection method to the manufacturing process of a semiconductor device having a chip structure having bumps, an LSI or the like in which semiconductor chips are mounted at high density via the bumps, etc. The manufacturing yield and reliability of can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the bump inspection method of the present invention will be specifically described below with reference to the process explanatory diagram shown in FIG. Further, a method of manufacturing a semiconductor device of the present invention will be specifically described with reference to the process explanatory diagrams of FIGS.

Referring to FIG. 2 (a), a plurality of Pb-5 wt% Sn alloy bumps 12A, 12B having a design dimension of a diameter of 100 μm and a height of about 50 μm are formed on a semiconductor substrate (chip) 11 by the method of the present invention. The sample 17 provided with the above components is inserted into the processing chamber 16 in which a non-oxidizing atmosphere of, for example, [nitrogen (N ₂ ) + hydrogen (H ₂ )] is maintained. A flat pressing glass plate 13 parallel to the upper surface of the sample substrate, that is, the semiconductor substrate is provided on the sample placement portion of the processing chamber 16 so as to be vertically movable, and the sample is provided on the ceiling of the processing chamber 16, for example. An infrared lamp 15 for heating is provided.

Referring to FIG. 2 (b), the pressing glass plate is then driven by the infrared lamp 15.
The Pb-5 wt% Sn alloy bump 12 through 13 is heated to a temperature close to its melting point (about 300 ° C.), for example, 280 ° C. to increase the plasticity of the bump 12, and the pressing glass is used. The plate 13 is dropped in parallel to the semiconductor substrate (chip) 11 surface of the sample, and pressure is applied from above to all the bumps 12A, 12B, etc., so that the height of all the bumps 12A, 12B, etc. The height of about 25 μm, which is 1/2 of the dimension height (h) (1
/ 2 h).

Here, the pressing parallel plate is not limited to the above glass plate, and may be made of metal as long as it is a material to which the bump material does not adhere and maintains a surface state where the bump material does not adhere. It doesn't matter if it's a thing.

Next, referring to FIG. 2 (c), the infrared lamp 15 is cut to stop heating the bumps 12A, 12B, etc., and then the pressing glass plate 13 is raised to separate it from the bumps 12A, 12B, etc. The sample 17 is taken out of the processing chamber 16.

Next, referring to FIG. 2D, the surface of the sample 17 is observed with a microscope from the upper side perpendicular to the semiconductor substrate 11, and this observed image is image-processed and binarized to obtain the bumps 12A to 12F. A distinction is made between 112A-112F and the other portion 111 of the substrate 11.

Then, the number of pixels of each of the bumps 12A to 12F etc. is individually counted, and the volume of each of the bumps 12A to 12F etc. is calculated. Here, the control value of the bump volume is set in advance to a predetermined distribution width, bumps that deviate from the control value are detected as defective bumps, and the quality of the semiconductor chip having the bumps is determined. In this embodiment, the bump 12B having an extremely small bump volume is easily and accurately determined as a defective bump.

In the above embodiments, the present invention has been described using the Pb-5 wt% Sn alloy bump which is most frequently used. However, the present invention is not limited to the above Pb / Sn alloy bump, but may be an In / Pb alloy or the like. It is of course applicable when using a bump made of a metal that is soft and has a low melting point.

Further, the P including the above-mentioned bump inspection method
A semiconductor device having a chip structure having b / Sn alloy bumps is manufactured by the following method, for example. See FIG. 3 (a). First, a semiconductor circuit (not shown) is formed, and a plurality of external connection pads made of aluminum (Al) alloy or the like are formed on the surface.
A coating insulating film is formed on the semiconductor substrate 21 on which 22A, 22B, etc. are formed.
23, and the pad for external connection is formed on the covering insulating film 23.
After forming the openings 24A, 24B, etc. exposing the 22A, 22B, etc., titanium (T:
i) Forming the film 25 and then forming a barrier metal with a thickness of 1000
A nickel (Ni) film 26 of about 5000 Å is formed.

Next, referring to FIG. 3 (b), the Ni is formed by a conventional photolithography means.
The film 26 is patterned to form Ni film patterns 26A, 26B and the like serving as barrier metal on the openings 24A, 24B and the like.

Next, as shown in FIG. 3 (c), a resist film 27 is formed on this substrate as usual,
Bump connection holes 28A, 28B etc. for exposing the Ni film patterns 26A, 26B etc. are formed in the resist film 27, and then the Ti film 25 is used as a cathode and the bump connection by the usual electroplating means. Above the openings 28A, 28B, etc.
The Pb / Sn alloy bumps 29A, 29B having a thickness of about 50 μm are formed.

Next, after removing the resist film 27, the Ti film 25 is patterned by using the Ni film patterns 26A and 26B as a mask to separate the individual bumps 29A and 29B from each other. To do.

Next, as in the embodiment of the bump inspection method, a pressing glass plate 13 on a flat plate parallel to the substrate is pressed onto this substrate, and the bumps 29A, 29B and the like are 25 μm thick. Crush to a uniform thickness.

Next, as shown in FIG. 3 (f), after the pressing glass plate 13 is removed, the image observed from directly above the upper surface of the substrate by a microscope or the like is binarized and crushed as in the bump inspection method. Bump 29A,
By measuring the plane area of 29B or the like, the distribution of the volume of all bumps arranged on the substrate is inspected, and the manufacturing process of the semiconductor device having bumps according to the present invention is completed.

[0026]

As described above, according to the present invention, three-dimensional bump volume fluctuations can be directly maintained by crushing a large number of bumps dispersedly arranged on a substrate to a certain height. By replacing with the dimensional variation of the plane area of the bump and measuring the plane area, it becomes possible to easily and highly accurately detect the variation of the volume of each bump. Further, according to the present invention, the plane area can be measured at high speed easily and accurately by binarizing the optical observation image of the bump and counting the number of pixels.

As described above, according to the present invention, it is possible to easily and accurately manage the volume distribution of the bumps that are dispersedly arranged on the substrate, and the semiconductor chips can be integrated and mounted at high density via the bumps. It is possible to improve the manufacturing yield and reliability of the manufactured LSI and the like.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a process explanatory view of an embodiment of a bump inspection method according to the present invention.

FIG. 3 is a process explanatory view of an embodiment of a method of manufacturing a semiconductor device according to the present invention.

[Explanation of symbols]

 1 semiconductor chip 2 bumps 3 parallel plate 4 vertical force 5 substrate heating 11 semiconductor substrate (chip) 12A to 12F Pb-5wt% Sn alloy bump 13 glass plate for pressing 15 infrared lamp 16 processing chamber 17 sample 111 binarized image Substrate part 112A to 112F Bump part of binarized image h Bump height h'Bump height forcibly aligned by crushing

Claims (4)

[Claims] 1. A bump inspection method for controlling the volume of a plurality of bumps dispersedly arranged on one substrate, comprising: pressing a substrate surface having the plurality of bumps with a flat plate parallel to the substrate. After crushing the plurality of bumps to a uniform height, the bump-arranged surface of the substrate is observed from directly above, and the volume of the bump is inspected based on the area occupied by the bump obtained from the observed image. A bump inspection method characterized by the above. 2. The area occupied by the bumps is measured by binarizing the observed image to distinguish the bump portion of each of the plurality of bumps from the portion other than the bumps, and the number of pixels of each bump portion is individually measured. The bump inspection method according to claim 1, wherein the bump inspection method is performed by counting. 3. The bump inspection method according to claim 1, wherein the bump is heated to a temperature lower than a melting point of the bump material when the bump is pressed to a uniform height. 4. A method of manufacturing a semiconductor device having bumps for external connection, comprising forming an insulating film on a semiconductor substrate on which a plurality of pads for bump placement are formed, and forming the plurality of pads on the insulating film. The opening which is individually exposed is formed, and bumps which are individually connected to the respective pads are formed in the plurality of opening portions, and then the openings are formed.
Alternatively, a method of manufacturing a semiconductor device, including the step of inspecting the volume of each bump by the bump inspection method described in 2 or 3.