Stable and lossless epitaxial wafer electrical performance testing device for EL testing system

Abstract

The utility model discloses a stable and lossless epitaxial wafer electrical performance testing device for an EL testing system. The stable and lossless epitaxial wafer electrical performance testing device comprises a current source, a P-pole testing probe and an N-pole testing electrode, wherein the P-pole testing probe and the N-pole testing electrode are connected with the current source; the P-pole test probe is a telescopic P-pole test probe and comprises a shell, a conductive spring is installed in the shell, one end of the spring is fixed to the top end of the shell and connected with a current source through a wire, the other end of the spring is connected with a P-pole test electrode, and the P-pole test electrode is controlled by a motor to move and directly make contact with the surface of an epitaxial wafer to be tested; the N-pole test electrode is an annular N-pole test electrode made of a flexible conductive material, and the annular N-pole test electrode wraps the exposed N layer of the side wall of the epitaxial wafer and is connected with a current source through a wire. The EL result tested by the device is stable and reliable, and can be used as a standard for judging the performance of the epitaxial wafer through verification, so that the quick test process can be canceled, the in-process period can be shortened, the situation that abnormity is not found in time can be avoided, and the electrical grade of each epitaxial wafer can be accurately endowed.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor material and photoelectric device testing, in particular to a stable and lossless epitaxial wafer electrical performance testing device for an EL testing system. Background Art

[0002] LED lighting products are rapidly replacing traditional lighting products, and the market size is expanding. In order to improve energy efficiency, protect the environment, and respond to global climate change, LED lighting products, as new energy-efficient lighting products, are key energy-saving lighting products promoted by countries around the world. Countries around the world have successively clarified the timetable for phasing out incandescent lamps.

[0003] At present, China has become the world's largest LED lighting production base, and its LED lighting market size continues to expand. In 2019, the scale of China's LED lighting market reached 682.3 billion yuan, and the penetration rate of LED lighting products reached 76%. The continuous innovation of LED lighting technology and the continuous reduction of product costs are important reasons for its success. Among them, the continuous advancement and innovation of testing technology is an important part of reducing costs.

[0004] In the production process of LED epitaxial wafers, judging and monitoring product performance is a necessary means of mass production. However, the current technology has the following defects: (1) Unstable contact: In electroluminescence detection, a micro-electrical probe is used to contact the two electrodes of the LED epitaxial wafer respectively and inject current to record the electrical and luminescent properties of the LED chip. However, due to the warping problem of the LED epitaxial wafer itself and the hard contact between the probe and the epitaxial wafer electrode, the contact is unstable. This may affect the accuracy of the test data. (2) Risk of damage: When performing electroluminescence detection, it is necessary to destroy the front of the LED epitaxial wafer before making the N electrode or a single hard-contact N electrode on the side. Because the thickness of various types of LED epitaxial wafers varies greatly, the damage risk and contact problems of this method are more obvious.

[0005] At present, when testing EL points on LED epitaxial wafers, the unstable contact between the P / N electrodes causes large fluctuations in test results, which in turn affects the judgment of epitaxial wafer performance monitoring. Currently, EL testing can only be used as a reference for epitaxial wafer performance monitoring, and cannot be used as a standard. To address this problem, the industry generally adopts the practice of selecting some sample wafers for the chip manufacturing process quick test process and taking back the quick test data.

[0006] However, this technology has inevitable disadvantages: assigning electrical grade to epitaxial wafers through rapid test and tape-back: 1. Long product manufacturing cycle (requires 3 days to obtain rapid test data as performance standard); 2. If the performance of the epitaxial wafer is abnormal, if it is not discovered until 3 days later, all products produced within these 3 days will be abnormal, causing huge losses; 3. The tape-back mechanism cannot truly present the electrical grade of each epitaxial wafer, and misjudgment may occur; 4. The test results of traditional epitaxial wafer electrical performance methods fluctuate greatly, which in turn affects the judgment of epitaxial wafer performance monitoring.

[0007] To solve the problem of unstable contact and damage, researchers have proposed some methods, such as covering the LED chip to be tested with a transparent conductive film or using contactless detection technology such as photoluminescence detection. These methods can reduce physical contact with the LED chip and thus reduce the risk of damage. Utility Model Content

[0008] In response to the problems mentioned in the background technology, the utility model proposes a stable and non-destructive epitaxial wafer electrical performance testing device for an EL testing system, which replaces the quick test and rewind process, solves the problems of long production cycle, untimely abnormality detection, and misjudgment of the electrical level of the epitaxial wafer by the rewind mechanism; at the same time, it reduces physical contact with the LED chip and reduces the risk of damage.

[0009] The technical solution adopted by the utility model is as follows:

[0010] A stable and non-destructive epitaxial wafer electrical performance testing device for an EL testing system, comprising a current source, a P-pole testing probe and an N-pole testing electrode connected to the current source;

[0011] The P-pole test probe is a retractable P-pole test probe, including a shell, a conductive spring installed in the shell, one end of the spring is fixed to the top of the shell and connected to the current source through a wire, and the other end is connected to the P-pole test electrode, and one end of the P-pole test electrode connected to the epitaxial wafer to be tested is a plane made of conductive material, and the P-pole test electrode is controlled by a motor to move and directly contact the surface of the epitaxial wafer to be tested; this design can effectively avoid the problem that the needle insertion depth is difficult to control during the test and the P-electrode contact is unstable due to the warping of the epitaxial wafer at room temperature;

[0012] The N-pole test electrode is an annular N-pole test electrode made of a flexible conductive material, which is coated on the exposed N layer on the side wall of the epitaxial wafer and connected to the current source through a wire; this design allows the N-pole test electrode to be in tight contact with the N layer, avoiding fluctuations in test results caused by unstable N-pole contact.

[0013] The conductive material includes silver, copper, gold, aluminum, indium tin alloy, etc.;

[0014] The flexible conductive material includes conductive polymers: for example, polymer matrices including polyethylene terephthalate (PET), polydimethylsiloxane (PDMS), polyurethane (PU), etc. and nano-conductive materials including graphene, carbon nanotubes, metal nanowires, etc. form flexible conductive materials; conductive rubber: for example, conductive silicone, which has good flexibility and conductive properties; conductive fiber fabric: conductive fibers are added to textiles to make them have conductive functions.

[0015] The annular N-pole test electrode is a whole piece of N-layer upper electrode coated on the exposed side wall of the epitaxial wafer or a plurality of annular pieces of N-layer upper electrodes uniformly arranged on the exposed side wall of the epitaxial wafer.

[0016] The above-mentioned testing method of the stable and non-destructive epitaxial wafer electrical performance testing device for the EL testing system comprises the following steps:

[0017] (1) Placing the epitaxial wafer on a base;

[0018] (2) placing the P-pole test electrode of the retractable P-pole test probe on the surface of the epitaxial wafer and connecting it to a current source via a wire, and coating the annular N-pole test electrode on the exposed N-layer on the side wall of the epitaxial wafer and connecting it to a current source via a wire;

[0019] (3) Set the acupressure parameters and conduct electrical parameter tests.

[0020] The EL results tested by the above method are stable and reliable. After verification, they can be used as the standard for judging the performance of epitaxial wafers. The quick test process can be eliminated, the production cycle can be shortened, the abnormality can be avoided from being discovered in time, and the electrical grade of each epitaxial wafer can be accurately assigned. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is an application state diagram of the device of the utility model.

[0022] Figure 2 It is a structural schematic diagram of a P-pole test probe in the device of the utility model.

[0023] Figure 3 This is an application state diagram of the N-pole test electrode in the device of the utility model in Example 1.

[0024] Figure 4 This is an application state diagram of the N-pole test electrode in the device of the utility model in Example 2.

[0025] Figure 5 This is a linear relationship diagram between the voltage value of the epitaxial wafer in the traditional EL test and the voltage value of the quick test.

[0026] Figure 6 It is a linear relationship diagram between the voltage value of the epitaxial wafer tested by the testing method of the present invention and the quick test voltage value. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the embodiment of the utility model clearer, the technical scheme in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. The components of the embodiment of the utility model generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiment of the utility model provided in the drawings is not intended to limit the scope of the utility model for protection, but merely represents the selected embodiment of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model. Example

[0028] like Figure 1 As shown, the EL test system includes: a control computer, a spectrometer, a light collecting device, a photoelectric converter, an optical fiber and a stable and non-destructive epitaxial wafer electrical performance testing device for the EL test system of the utility model, the device includes a P-pole test probe 100, an annular N-pole test electrode 200, a driving current and voltage source 300 and a control motor 400.

[0029] like Figure 2 As shown, the P-pole test probe in the present invention is a retractable P-pole test probe 100, including a shell 101, a conductive spring 102 is installed in the shell, one end of the spring is fixed to the top of the shell and connected to the driving current and voltage source 300 through a wire, and the other end is connected to the P-pole test electrode 103, and one end of the P-pole test electrode connected to the epitaxial wafer 500 to be tested is a plane 1031 made of conductive material; this design can effectively avoid the problem that the needle depth is difficult to control during the test and the P-electrode contact is unstable due to the warping of the epitaxial wafer at room temperature;

[0030] like Figure 3 The N-pole test electrode in the utility model is an annular N-pole test electrode made of a flexible conductive material, which is coated on the exposed N layer on the side wall of the epitaxial wafer and connected to the driving current and voltage source 300 through a wire; this design allows the N-pole test electrode to be in tight contact with the N layer, avoiding fluctuations in test results caused by unstable N-pole contact.

[0031] During the test, the epitaxial wafer is placed on the base 600; the P-pole test electrode of the retractable P-pole test probe is placed on the surface of the epitaxial wafer and connected to the driving current and voltage source through a wire, and the annular N-pole test electrode is coated on the exposed N layer of the epitaxial wafer side wall and connected to the current source through a wire; the needle pressure parameters are set and the electrical parameter test is performed. The control motor drives the retractable P-pole test probe to automatically move on the surface of the epitaxial wafer to complete the test of the entire epitaxial wafer.

[0032] Figure 5 There is a linear relationship between the voltage value of the epitaxial wafer in the traditional EL test and the quick test voltage value. It can be seen that there is no correlation between the two and they cannot be used for grade determination.

[0033] Figure 6 The test method of the present invention shows a linear relationship between the voltage value of the epitaxial wafer tested and the quick test voltage value. It can be seen that the two are highly correlated and have the same trend, which can be used for grade determination. Example

[0034] The difference between this embodiment and embodiment 1 is that the annular N-pole test electrode in embodiment 1 is arranged as 4 annular upper electrodes uniformly arranged on the exposed N layer of the epitaxial wafer side wall.

[0035] In the description of the present utility model, it should be noted that when terms such as "upper", "lower", "inner", "outer", "left", "right" and the like indicating orientation or positional relationship appear, it should be understood that the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed when in use, or the orientation or positional relationship commonly understood by those skilled in the art, is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the equipment or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, when terms such as "first" and "second" appear, they are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present utility model, it should also be noted that, unless otherwise clearly specified and limited, terms such as "installation", "setting", and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements. For those skilled in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

Claims

1. A stable and non-destructive epitaxial wafer electrical performance testing device for an EL testing system, characterized in that: It includes a current source, a P-pole test probe and an N-pole test electrode connected to the current source; The P-pole test probe is a retractable P-pole test probe, comprising a shell, a conductive spring installed in the shell, one end of the spring is fixed to the top of the shell and connected to the current source through a wire, and the other end is connected to the P-pole test electrode, one end of the P-pole test electrode connected to the epitaxial wafer to be tested is a plane made of conductive material, and the P-pole test electrode is controlled by a motor to move and directly contact the surface of the epitaxial wafer to be tested; The N-pole test electrode is an annular N-pole test electrode made of a flexible conductive material, which is coated on the exposed N layer on the side wall of the epitaxial wafer and connected to a current source through a wire.

2. The epitaxial wafer electrical performance testing device according to claim 1, characterized in that: The conductive material includes silver, copper, gold, aluminum, and indium tin alloy.

3. The epitaxial wafer electrical performance testing device according to claim 1, characterized in that: The flexible conductive material includes conductive polymer, conductive rubber, and conductive fiber fabric.

4. The epitaxial wafer electrical performance testing device according to claim 3, characterized in that: The conductive polymer is a flexible conductive material formed by a polymer matrix including polyethylene terephthalate, polydimethylsiloxane, and polyurethane and a nano conductive material including graphene, carbon nanotubes, and metal nanowires.

5. The epitaxial wafer electrical performance testing device according to claim 3, characterized in that: The conductive rubber includes conductive silicone rubber.

6. The epitaxial wafer electrical performance testing device according to claim 3, characterized in that: The conductive fiber fabric is a textile with conductive fibers added.

7. The epitaxial wafer electrical performance testing device according to claim 1, characterized in that: The annular N-pole test electrode is a whole piece of N-layer upper electrode coated on the exposed side wall of the epitaxial wafer or a plurality of annular pieces of N-layer upper electrodes uniformly arranged on the exposed side wall of the epitaxial wafer.

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