Substrate manufacturing method and semiconductor device manufacturing method

Abstract

This method for manufacturing a substrate involves: immersing, in pure water or a corrosive solution, the substrate having a plurality of circuit patterns formed thereon; applying a voltage between the plurality of circuit patterns while the substrate is immersed in the pure water or the corrosive solution; determining that the substrate is a defective product when a tree is generated due to the applying of the voltage to the plurality of circuit patterns; and determining that the substrate is a good product when no tree is generated.

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a substrate and a method for manufacturing a semiconductor device. [Background technology]

[0002] Patent Document 1 discloses an electrochemical migration evaluation system. This evaluation system includes a thermo-hygrostat that stores electrodes for which electrochemical migration (ECM) is to be evaluated, and a power supply device that applies a voltage between the electrodes. The evaluation system further includes an impedance calculation means, an evaluation means, and an imaging device. The impedance calculation means measures the current flowing between the electrodes and calculates the impedance between the electrodes based on the measurement results. The evaluation means performs ECM evaluation between the electrodes based on the impedance calculation results. The imaging device captures an image of the surface of the electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-153886 Summary of the Invention [Problem to be solved by the invention]

[0004] The evaluation system of Patent Document 1 requires measurements using an impedance detection circuit to detect defects, which may make it difficult to detect defects.

[0005] An object of the present disclosure is to provide a method for manufacturing a substrate and a method for manufacturing a semiconductor device that enable easy detection of defects. [Means for solving the problem]

[0006] The manufacturing method for a substrate according to the first disclosure involves immersing a substrate on which a plurality of circuit patterns have been formed in pure water or a corrosive solution, applying a voltage between the plurality of circuit patterns while the substrate is immersed in the pure water or the corrosive solution, and determining the substrate as defective if treeing occurs in the plurality of circuit patterns due to the application of the voltage, and determining the substrate as pass-through if no treeing occurs.

[0007] A manufacturing method for a semiconductor device according to the second disclosure includes immersing a substrate on which a plurality of circuit patterns are formed in pure water or a corrosive solution, applying a voltage between the plurality of circuit patterns while the substrate is immersed in the pure water or the corrosive solution, determining the substrate as defective if treeing occurs in the plurality of circuit patterns due to the application of the voltage, determining the substrate as passable if no treeing occurs, and mounting a semiconductor chip on the substrate determined to be passable. Effect of the Invention

[0008] In the substrate manufacturing method according to the first disclosure and the semiconductor device manufacturing method according to the second disclosure, defects can be easily detected based on the presence or absence of trees. [Brief description of the drawings]

[0009] [Figure 1] 1 is a plan view of a substrate inspection device according to a first embodiment. [Diagram 2] 4 is a flowchart showing a method for manufacturing the semiconductor device according to the first embodiment. [Diagram 3] FIG. 1 illustrates an example of a tree. [Figure 4] 1 is a cross-sectional view of a semiconductor device according to a first embodiment. [Diagram 5] 10 is a flowchart showing a method for manufacturing a semiconductor device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for manufacturing a substrate and a method for manufacturing a semiconductor device according to each embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0011] Embodiment 1 1 is a plan view of a substrate inspection device 100 according to embodiment 1. The inspection device 100 includes a case 10 that holds an immersion liquid 14 such as pure water or a corrosive solution, and a voltage application circuit 12 that applies a voltage to an object to be inspected. The case 10 is insulating and made of plastic or the like. In this embodiment, pure water is used as the immersion liquid 14.

[0012] The inspection target is a substrate 30. The substrate 30 is also called an insulating substrate or a ceramic substrate. The substrate 30 has an insulating layer 32 and a plurality of circuit patterns 34 formed on the surface of the insulating layer 32. The insulating layer 32 is made of a ceramic such as SiN. The plurality of circuit patterns 34 are formed by bonding a metal layer such as Cu or Al to the insulating layer 32. The metal layer may be formed on both sides of the insulating layer 32. Of the metal layers, the one formed on the surface of the insulating layer 32 is called the circuit pattern 34. The surface of the insulating layer 32 is the surface on which a semiconductor chip is mounted.

[0013] The multiple circuit patterns 34 are spaced apart from one another. The voltage application circuit 12 is a circuit for applying a voltage between the multiple circuit patterns 34 from an external power source 16 while the substrate 30 is immersed in the immersion liquid 14.

[0014] Fig. 2 is a flowchart showing a method for manufacturing a semiconductor device according to the first embodiment. The method for manufacturing a semiconductor device using the inspection device 100 will be described with reference to Fig. 2. First, in step 1, pure water is poured into the case 10. Next, in step 2, the substrate 30 is immersed in the pure water. At this time, it is preferable that the entire substrate 30 is immersed in the pure water.

[0015] Next, in step 3, while the substrate 30 is immersed in pure water, a voltage is applied between the multiple circuit patterns 34. At this time, the electrodes of the voltage application circuit 12 are brought into contact with the circuit patterns 34, and a voltage is applied from the external power source 16. The voltage between the electrodes is, for example, 20 V.

[0016] Next, in step 4, the presence or absence of trees is confirmed. In step 3, the metal in the circuit pattern 34 may react with water, causing electrochemical migration. At this time, metal ions are generated on the anode side, and metal is precipitated on the cathode side. As a result, trees are observed. In this way, the presence or absence of trees can be used to confirm the occurrence of ion migration. The tendency for trees to occur generally corresponds to the tendency for the insulating substrate to deteriorate in withstand voltage. This is because the more a product is exposed to high humidity, the lower the withstand voltage generally becomes.

[0017] Fig. 3 is a diagram showing an example of a tree 80. In the example of Fig. 3, in a region where the anode 35 and the cathode 36 are adjacent to each other, a tree 80 has occurred on the cathode 36 side. The presence or absence of tree occurrence is confirmed by using, for example, a microscope.

[0018] If trees are found in step 4, proceed to step 5 and discard the substrate 30. If no trees are found in step 4, proceed to step 6. In this way, if trees are found in multiple circuit patterns 34 due to the application of voltage, the substrate 30 is determined to be defective, and if no trees are found, the substrate 30 is determined to be non-defective.

[0019] Next, in step 6, the substrate 30 determined to be a non-defective product is cleaned. The subsequent steps will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the semiconductor device 60 according to the first embodiment. In step 7, a semiconductor chip 40 is mounted on the substrate 30 determined to be a non-defective product. The semiconductor chip is, for example, a power semiconductor chip. Next, in step 8, the substrate 30 is mounted on a base plate 42. Next, in step 9, wire bonding is performed. In wire bonding, wires 44 are used to connect between the semiconductor chips 40, between the semiconductor chip 40 and the circuit pattern 34, between the circuit patterns 34, and so on.

[0020] Next, terminal bonding is performed in step 10. Here, for example, terminal 46 and circuit pattern 34 are bonded. Next, case bonding is performed in step 11. Here, case 48 is bonded to base plate 42. Next, terminal bending is performed in step 12. Here, terminal 46 is bent. Next, gel sealing and lid closing are performed in step 13. Here, the inside of case 48 is sealed with sealant 50. Also, lid 52 is mounted on top of case 48. With the above steps, semiconductor device 60 is completed. Semiconductor device 60 is, for example, a power semiconductor device.

[0021] In this embodiment, the occurrence of electrochemical migration can be easily confirmed by immersing the substrate 30 in pure water and applying a voltage between the circuit patterns 34. This makes screening easy, and is expected to lead to improved quality. Also, in this embodiment, defects can be detected by removing the substrate 30 from the immersion liquid 14 and checking for the presence or absence of trees. This makes it possible to suppress further electrochemical reactions from occurring in the process of determining the presence or absence of defects. Also, defects can be detected in a short period of time.

[0022] The time from immersing the substrate 30 in the immersion liquid 14 to determining whether or not there is a tree may be performed within 330 seconds. In other words, steps 1 to 4 may be performed within 330 seconds. Such a rapid inspection is expected to improve quality.

[0023] In addition, the electric field applied between the plurality of circuit patterns 34 by the voltage applied between the plurality of circuit patterns 34 is preferably 10 V / mm or more. By setting the electric field to 10 V / mm or more, an electrochemical reaction can be generated. This allows for accurate detection of defects based on the presence or absence of trees.

[0024] The semiconductor chip 40 may be made of a wide band gap semiconductor. The wide band gap semiconductor is, for example, silicon carbide, a gallium nitride material, or diamond. According to this embodiment, even if the semiconductor chip 40 is made of a wide band gap semiconductor and a high current flows, defects can be easily detected in the manufacturing process of the semiconductor device 60, and the reliability can be improved.

[0025] The above-mentioned modifications can be appropriately applied to the substrate manufacturing method and the semiconductor device manufacturing method according to the following embodiments. Note that the substrate manufacturing method and the semiconductor device manufacturing method according to the following embodiments have many points in common with the first embodiment, so the differences from the first embodiment will be mainly described.

[0026] Embodiment 2 5 is a flowchart showing a method for manufacturing a semiconductor device according to embodiment 2. This embodiment differs from embodiment 1 in that a corrosive solution is used as the immersion liquid 14. The corrosive solution contains, for example, sulfur. The other manufacturing steps are the same as those of embodiment 1.

[0027] The corrosive solution can be obtained by mixing a corrosive gas with pure water. This makes it possible to produce a corrosive solution while preventing the mixing of unwanted substances. Examples of corrosive gases that can be used include sulfur gas, chlorine gas, and sulfurous acid gas.

[0028] The method of manufacturing the semiconductor device of this embodiment will be described below. First, in step 201, a corrosive solution is poured into the case 10. Steps 202 to 213 are the same as steps 2 to 13 of the first embodiment, respectively.

[0029] In this embodiment, the electrochemical reaction can be activated by mixing the pure water with a corrosive gas, thereby improving the accuracy of detecting defects.

[0030] The technical features described in each embodiment may be used in appropriate combination. [Explanation of symbols]

[0031] 10 case, 12 voltage application circuit, 14 immersion liquid, 16 external power supply, 30 substrate, 32 insulating layer, 34 circuit pattern, 35 anode, 36 cathode, 40 semiconductor chip, 42 base plate, 44 wire, 46 terminal, 48 case, 50 sealing body, 52 lid, 60 semiconductor device, 80 tree, 100 inspection device

Claims

1. The substrate on which a plurality of circuit patterns are formed is immersed in pure water or a corrosive solution, applying a voltage between the plurality of circuit patterns while the substrate is immersed in pure water or a corrosive solution; A method for manufacturing a substrate, comprising: discriminating the substrate as defective if tree generation due to application of the voltage occurs in the plurality of circuit patterns; and discriminating the substrate as non-defective if no tree generation occurs.

2. Immersing the substrate in the corrosive solution; 2. The method of claim 1, wherein the corrosive solution is obtained by mixing a corrosive gas with pure water.

3. 3. The method for manufacturing a substrate according to claim 1, wherein the corrosive solution contains sulfur.

4. 4. The method for manufacturing a substrate according to claim 1, wherein an electric field applied between the plurality of circuit patterns by the voltage is 10 V / mm or more.

5. 5. The method of manufacturing a substrate according to claim 1, wherein the time from immersing the substrate in pure water or a corrosive solution to determining whether or not a tree exists is within 330 seconds.

6. The substrate on which a plurality of circuit patterns are formed is immersed in pure water or a corrosive solution, applying a voltage between the plurality of circuit patterns while the substrate is immersed in pure water or a corrosive solution; discriminating the board as defective when a tree is generated in the plurality of circuit patterns due to the application of the voltage, and discriminating the board as non-defective when the tree is not generated; A method of manufacturing a semiconductor device, comprising the steps of: mounting a semiconductor chip on the substrate determined to be a non-defective product.

7. 7. The method for manufacturing a semiconductor device according to claim 6, wherein the semiconductor chip is made of a wide band gap semiconductor.

8. 8. The method for manufacturing a semiconductor device according to claim 7, wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material or diamond.

Images