Light source arrangement in a test system

Abstract

The application provides a light source device in a test system, characterized in that the device comprises: an optical mirror for reflecting light; a light source for providing light required for testing, wherein the light source has a light emitting surface; a probe board card arranged below the light source, wherein the probe board card is provided with a through hole; and a wafer arranged below the probe board card, wherein the wafer is provided with a chip photosensitive surface. By using the reflection mode, the optical path of light emitted by the light source to the wafer surface is enlarged in a smaller space; and by selecting light sources with different divergence angles, different wafer ranges can be covered; only according to the opening rule and the light source space position placement rule, the chips with different sizes of chip photosensitive surfaces can be completely covered by light, and further, by placing the light source on an independent PCB, the maintenance and replacement in the later stage are facilitated.

Description

Technical Field

[0001] This application relates to the field of chip testing, and in particular to the field of light source devices for chip testing systems. Background Technology

[0002] IC chips require two critical testing stages: chip probing (CP) and final test (FT). CP testing is a wafer-level chip test performed before packaging. FT testing is the final test conducted after chip packaging. CP testing uses specialized probes to directly apply stimulus signals to each chip on the wafer, testing the functionality of each chip. Failures in different areas are indicated by different colors. After CP testing, the wafer is diced, and the diced chips are sorted according to the results. Only the good chips are sent to the packaging plant for packaging. CP testing not only filters out defective chips, saving packaging costs, but also accommodates multiple chip tests, reducing the number of tests required in FT testing and improving overall testing efficiency.

[0003] For wafer-level chip testing, the probe board uses through-holes to provide complete light coverage (covering the photosensitive area of ​​the chip). During chip testing, the photosensitive area of ​​the chip needs to be covered by light through the through-holes of the probe board. However, traditional wafer testing light sources, combined with testing machines, are not only complex in structure and large in size, but also have problems such as complicated operation and high cost. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of the prior art by providing a light source device in a testing system. This device uses reflection to extend the optical path of the light emitted from the light source to the wafer surface within a smaller space. Furthermore, by selecting light sources with different divergence angles, different wafer ranges can be covered. By simply following the rules for opening and the spatial placement of the light source, complete light coverage of the photosensitive surfaces of chips of different sizes can be achieved. Moreover, by placing the light source on an independent PCB board, it is convenient for later maintenance and replacement.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0006] This application provides a light source device in a testing system, characterized in that it includes:

[0007] An optical mirror is used to reflect light.

[0008] A light source, used to provide the light required for the test, wherein the light source has a light-emitting surface;

[0009] A probe board is disposed below the light source, and the probe board has through holes;

[0010] A wafer is disposed below the probe board, and the wafer has a chip photosensitive surface.

[0011] Optionally, the angle between the optical mirror and the wafer in the horizontal direction is zero.

[0012] Optionally, the maximum horizontal distance between the center of the light source and the center of the through hole is determined by the horizontal dimensions of the through hole, the horizontal dimensions of the chip photosensitive surface, the distance from the lower surface of the optical mirror to the chip photosensitive surface in the vertical axis direction, the distance from the upper surface of the probe board to the light-emitting surface of the light source in the vertical direction, the thickness of the probe board, and the distance from the lower surface of the probe board to the chip photosensitive surface in the vertical direction.

[0013] Optionally, the minimum horizontal distance between the center of the light source and the center of the through hole is determined by the horizontal dimensions of the through hole, the horizontal dimensions of the chip photosensitive surface, the horizontal dimensions of the light source, the distance from the lower surface of the optical mirror to the chip photosensitive surface in the vertical axis direction, the distance from the upper surface of the probe board to the light-emitting surface of the light source in the vertical direction, the thickness of the probe board, and the distance from the lower surface of the probe board to the chip photosensitive surface in the vertical direction.

[0014] Optionally, the distance from the center of the light source to the edge of the through hole is not directly related to the horizontal dimension of the photosensitive surface of the chip.

[0015] Optionally, the light source is mounted on a separate PCB board.

[0016] Optionally, the optical mirror and the wafer are at a certain angle in the horizontal direction.

[0017] Optionally, the vertical distance of the optical mirror relative to the wafer is obtained based on the difference in dimensions between the chip's light-emitting surface and the via in the horizontal direction, the vertical distance of the probe board's upper surface relative to the chip's light-emitting surface, and the size of the light source.

[0018] Optionally, the horizontal position of the center of the light source relative to the center of the via can be obtained based on the difference in size between the chip's light-emitting surface and the via in the horizontal direction, the vertical distance between the upper surface of the probe board and the chip's light-emitting surface, the size of the light source, and the vertical distance between the optical mirror and the wafer.

[0019] The beneficial effects of this application are:

[0020] This application provides a light source device in a testing system, characterized in that it includes:

[0021] An optical mirror is used to reflect light.

[0022] A light source, used to provide the light required for the test, wherein the light source has a light-emitting surface;

[0023] A probe board is disposed below the light source, and the probe board has through holes;

[0024] A wafer is disposed below the probe board, and the wafer has a chip photosensitive surface.

[0025] By employing a reflection method, the optical path of the light emitted by the light source to the wafer surface is extended within a smaller space; moreover, by selecting light sources with different divergence angles, different wafer ranges can be covered; by simply following the rules for aperture and the spatial placement of the light source, complete light coverage of the photosensitive surface of chips of different sizes can be achieved; furthermore, by placing the light source on a separate PCB board, it is convenient for later maintenance and replacement. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a probe card detection method provided by existing technology;

[0028] Figure 2 This is a schematic diagram of a reflective optical system in a chip testing system provided in an embodiment of this application;

[0029] Figure 3 This application provides a schematic diagram of the light source position in a chip testing system for a reflective optical module.

[0030] Figure 4 This is a schematic diagram of a reflective optical system in another chip testing system provided in an embodiment of this application. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] Figure 1 A schematic diagram of a probe card detection method provided for existing technology; such as Figure 1 The schematic diagram shown includes a wafer 101 to be tested; a probe head 102; a pad 103; and a PCB board 104 that performs the main structural functions in the probe card. In wafer-level testing, a probe card with multiple conductive probes is used to transmit the test signals output by the test equipment to the semiconductor wafer. Typically, in wafer-level testing, the probe card 102 is used to detect the dies on the semiconductor wafer, with each probe individually contacting the pad 103 of each die. By making contact with the conductive probes, a test signal is input to facilitate inspection and detect defective products.

[0035] Figure 2 This application provides a schematic diagram of a reflective optical system in a chip testing system, as shown in the embodiments of the present application. Figure 2 The diagram shows an optical reflector 201, a light source 202, a PCB board 203, a probe board 204, a chip photosensitive surface 205, and a wafer 206. Figure 2 In the illustrated embodiment, the optical reflector 201 is positioned above the probe board 204. The light source 202 can be mounted on the probe board 204 or on a separate PCB board 203 for easy replacement. When the light source 202 is positioned on the separate PCB board 203, the separate PCB board 203 is positioned between the optical reflector 201 and the probe 204. The probe board has through-holes. The wafer 206 is positioned below the probe board, and the photosensitive area on the wafer is 205. Figure 2 In the illustrated embodiment, the optical mirror 201 is parallel to the wafer 206. Figure 2In the diagram, Z1 is the distance from the lower surface of the optical reflector 201 to the photosensitive surface 205 of the chip along the Z-axis; Z2 is the distance from the upper surface of the probe board 204 to the light-emitting surface 202 of the light source along the Z-axis; Z3 is the thickness of the probe board 204; Z4 is the distance from the lower surface of the probe board 204 to the photosensitive surface 205 of the chip along the Z-axis; Z5 is the distance from the upper surface of the probe board 204 to the photosensitive surface 205 of the chip along the Z-axis, where Z5 = Z3 + Z4; X1 is the dimension of the through hole of the probe board 204 along the X-axis; X2 is the dimension of the photosensitive surface 205 of the chip along the X-axis; X3 is the distance from the center of the light-emitting surface of the light source 202 to the center of the through hole of the probe board 204 along the X-axis; X4 is the dimension of the light source 202 along the X-axis; X5 is the distance from the edge of the through hole on the probe board to the edge of the photosensitive area 205 of the chip along the X-axis, X5 = (X1 - X2) / 2. Figure 2 In the illustrated embodiment, a light source 202 and an optical mirror 201 are placed above a probe board 204. The light source is horizontally positioned with its emitting surface facing away from the surface of the probe board 204. The light source can be mounted on the upper surface of the probe board 204 or on a separate PCB board 203. The mirror surface of the optical mirror 201 faces the probe board 204. The divergent light emitted by the light source 202 is reflected and passes through the through-hole of the probe board 204 to reach the photosensitive area 205 of the chip. By designing the spatial positions of the light source 202 and the optical mirror 201, and the opening size of the probe board 204, complete light coverage of chips with different photosensitive area sizes can be achieved.

[0036] Figure 3 This is a schematic diagram showing the position of the light source in a reflective optical module of a chip testing system provided in an embodiment of this application. Figure 3 The diagram shows an optical reflector 301, a light source 302, a PCB board 303, a probe board 304, a chip photosensitive surface 305, and a wafer 306. Figure 3 In the illustrated embodiment, the optical reflector 301 is positioned above the probe board 304. The light source 302 can be mounted on the probe board 304 or on a separate PCB board 303 for easy replacement. When the light source 302 is positioned on the separate PCB board 303, the separate PCB board 303 is positioned between the optical reflector 301 and the probe 304. The probe board has through-holes. The wafer 306 is positioned below the probe board, and the photosensitive area on the wafer is 305. Figure 3 The implementation column shown is Figure 2The illustrated embodiment is similar, with the optical mirror 301 parallel to the wafer 306. To ensure that the light emitted from the center of the light source completely covers the photosensitive area of ​​the chip, a virtual light ray can be drawn from the edge of the chip's photosensitive surface to the upper edge of the via. This virtual light ray propagates in the opposite direction and is reflected back to the center of the light source by the mirror. The location of this light source is the furthest distance x3 that can be reached from the center of the light source to the center of the via. max Calculations show that:

[0037] X3 max ≤X5 / Z5*(2*Z1-Z2-Z5)+X2 / 2 (1)

[0038] Depend on Figure 3 As is known, to avoid the light source itself blocking the light and affecting the photosensitive surface of the chip, the upper edge of the light source, the edge of the photosensitive surface of the chip, and the upper edge of the via should be in a straight line. This yields the minimum distance X3 from the center of the light source to the center of the via. min Calculations show that:

[0039] X3 min ≥X5 / Z5*(Z2+Z5)+X2 / 2+X4 / 2 (2)

[0040] As can be seen from equations (1) and (2), the distance (X3-X1 / 2) from the center of the light source to the edge of the via is not affected by the size X2 of the chip's photosensitive surface. Therefore, as long as the corresponding aperture rules and the range of distances from the center of the light source to the edge of the via are satisfied, light coverage of chips of any photosensitive area size can be achieved.

[0041] Figure 4 A schematic diagram of a reflective optical system in another chip testing system provided in this application embodiment is shown below. Figure 4 The diagram shows an optical reflector 401, a light source 402, a PCB board 403, a probe board 404, a chip photosensitive surface 405, and a wafer 306. Figure 4 In the illustrated embodiment, the optical reflector 401 is positioned above the probe board 404. The light source 402 can be mounted on the probe board 404 or on a separate PCB board 403 for easy replacement. When the light source 402 is positioned on the separate PCB board 403, the separate PCB board 403 is positioned between the optical reflector 401 and the probe 404. The probe board has through-holes. The wafer 406 is positioned below the probe board, and the photosensitive area on the wafer is 405. Figure 3 In the embodiment shown, the optical mirror 401 and the wafer 406 are at a certain angle and are in a non-parallel state.

[0042] exist Figure 4In the illustrated implementation, the center of the reflector 401 is taken as the origin, the horizontal direction is the X-axis, and the vertical direction is the Z-axis. Five key nodes are selected: the origin (x0, z0), the center of the light source's exit surface (x1, z1), the two edges of the chip's photosensitive area (x2, z2) and (x3, z3), and the two edge points on both sides of the through-hole (x4, z4) and (x5, z5). The rotation angle α of the reflector around the origin is... Figure 4 The meanings of Z1~Z5 and x1~x5 in the embodiments shown are the same as those of the previous embodiments. Figure 3 The embodiments shown are the same, so they will not be described again here.

[0043] like Figure 4 As shown, a beam of light passes through the edge of the via and reaches the edge of the chip. This beam is called the critical ray. When the angle of incidence is greater than the critical ray angle, the photosensitive surface of the chip is shadowed; when the angle of incidence is less than the critical ray angle, the photosensitive surface of the chip is fully covered. The critical ray is considered as a straight line, as shown in formula (3):

[0044]

[0045] If the projection of the plane containing the mirror onto the ZX plane is considered as a straight line, the formula is:

[0046] z=x·tan(α) (4)

[0047] The coordinates of the point where the two straight lines coincide, which is also the critical ray at the point of reflection on the mirror, are (x...). s ,z s ),

[0048]

[0049] z s =x s ·tanα (6)

[0050] The angle between the critical ray and the reflecting surface is θ, and its magnitude is...

[0051]

[0052] The critical ray's reflection angle is γ, and its magnitude is...

[0053] γ=90°+θ (8)

[0054] The angle between the incident ray and the horizontal plane corresponding to the critical ray is ∈, and its magnitude is .

[0055] ∈=180°-(θ+2γ-α) (10)

[0056] The formula for the incident ray corresponding to the critical ray is:

[0057] z = tan(ε)·x - (x s ·tan(ε)-z s (11)

[0058] From formula (11), it can be seen that by substituting the vertical position z of the light-emitting surface of the light source into the formula, we can obtain the maximum distance x from the center of the light source to the center of the through hole.

[0059]

[0060] Figure 4 In the embodiment shown, the distance of the reflective surface relative to the wafer is first obtained based on the size difference between the chip and the via, the distance of the probe board surface relative to the chip, and the size of the light source. Then, the position of the center of the light source relative to the center of the via is obtained to ensure that the light source fully covers the photosensitive surface of the chip.

[0061] exist Figure 4 In the embodiment shown, the distance from the upper surface of the probe board to the photosensitive surface of the wafer is Z5. min ~Z5 max The maximum size of the chip's photosensitive area is: X2 max *X2 max ;

[0062] The maximum size of the light source is: X4 max *X4 max The vertical distance between the light-emitting surface of the light source and the probe board is Z2. min ~Z2 max The tilt angle range of the reflecting surface is ±α.

[0063] The distance from the chip edge to the via edge is: X5 min ~X5 max ;

[0064] The shortest vertical distance between the reflecting surface and the wafer is Z1 according to the formula. min for

[0065]

[0066] To ensure sufficient spatial margin for the light source in the horizontal direction, the vertical distances between the reflecting surface and the wafer surface are increased by 5mm and 15mm respectively, based on the minimum distance, resulting in:

[0067] Z1=Z1 min +5mm~Z1 min +15mm (14)

[0068] If α = 0, substituting formula (14) into formulas (1) and (2), we obtain the horizontal distance between the center of the light source and the center of the through hole as: X3 min ~X3max Distance from the center of the light source to the edge of the through hole: X3 min -X1 / 2~X3 max -X1 / 2

[0069] If α≠0, substitute formula (14) and angle α into formula (12) and formula (2) to calculate the horizontal distance between the center of the light source and the center of the through hole: X3 min ~X3 max .

[0070] according to Figure 4 In the embodiment shown, the distance from the upper surface of the probe board to the photosensitive surface of the wafer is 5mm to 8mm; the maximum size of the photosensitive area of ​​the chip is 4mm*4mm; the maximum size of the light source is 5mm*5mm; and the vertical distance between the light-emitting surface of the light source and the probe board is 3mm to 5mm.

[0071] The tilt angle α of the projection surface is 0; the distance from the chip edge to the via edge is 0.5mm to 1mm; according to Figure 4 The following embodiments show that the shortest vertical distance between the reflecting surface and the wafer is 30.5 mm; the distance between the reflecting surface and the wafer is 35.5 mm to 45.5 mm; the distance from the center of the light source to the center of the via is 5.3125 mm to 5.75 mm; and the distance from the center of the light source to the edge of the via is 2.8125 mm to 3.25 mm.

[0072] Assume the distance from the upper surface of the probe board to the photosensitive surface of the wafer is 5mm–8mm; the maximum size of the chip's photosensitive area is 4mm*4mm; the maximum size of the light source is 5mm*5mm; the vertical distance between the light-emitting surface of the light source and the probe board is 3mm–5mm; the tilt angle α of the emitting surface is 0; the distance from the chip edge to the edge of the via is 1mm–1.5mm; according to Figure 4 The embodiment shown yields the following: the shortest vertical distance between the reflective surface and the wafer is 20.5 mm; the distance between the reflective surface and the wafer is 25.5 mm to 35.5 mm; the distance from the center of the light source to the center of the via is X3 = 6.125 mm to 7 mm; and the distance from the center of the light source to the edge of the via is 3.12 mm to 4 mm.

[0073] Assuming the distance from the top surface of the probe board to the photosensitive surface of the wafer is 5mm–8mm; the maximum size of the chip's photosensitive area is 4mm*4mm; the maximum size of the light source is 5mm*5mm; the vertical distance between the light-emitting surface of the light source and the probe board is 3mm–5mm; the tilt angle α of the emitting surface is 0; and the distance from the chip edge to the edge of the via is 1.5mm–2mm; through… Figure 4The embodiment shown yields the following: the shortest vertical distance between the reflective surface and the wafer is 17.1667 mm; the distance between the reflective surface and the wafer is 22.1667 mm to 32.1667 mm; the distance from the center of the light source to the center of the via is 6.9375 mm to 8.25 mm; and the distance from the center of the light source to the edge of the via is 3.437 mm to 4.75 mm.

[0074] Assume the distance from the upper surface of the probe board to the photosensitive surface of the wafer is 5mm to 8mm; the maximum size of the photosensitive area of ​​the chip is 4mm*4mm; the maximum size of the light source is 5mm*5mm; the vertical distance between the light-emitting surface of the light source and the probe board is 3mm to 5mm; the tilt angle of the light-emitting surface is α = ±1°; and the distance from the edge of the chip to the edge of the via is 0.75mm to 1mm.

[0075] pass Figure 4 The following embodiments show that the shortest vertical distance between the reflecting surface and the wafer is 23.8 mm, the distance between the reflecting surface and the wafer is 28.8 mm to 38.8 mm, the distance from the center of the light source to the center of the via is 5.72 mm to 6.06 mm, and the distance from the center of the light source to the edge of the via is 0.97 mm to 3.31 mm.

[0076] Assume the distance from the top surface of the probe board to the photosensitive surface of the wafer is 5mm–8mm; the maximum size of the chip's photosensitive area is 4mm*4mm; the maximum size of the light source is 5mm*5mm; the vertical distance between the light-emitting surface of the light source and the probe board is 3mm–5mm; the tilt angle α of the emitting surface is ±1°; the distance from the chip edge to the edge of the via is 1mm–1.5mm; through… Figure 4 The embodiment shown yields the following: the shortest vertical distance between the reflective surface and the wafer is 20.5 mm; the distance between the reflective surface and the wafer is 25.5 mm to 35.5 mm; the distance from the center of the light source to the center of the via is 6.125 mm to 6.72 mm; and the distance from the center of the light source to the edge of the via is 3.125 mm to 3.74 mm.

[0077] Assume the distance from the upper surface of the probe board to the photosensitive surface of the wafer is 5mm–8mm; the maximum size of the chip's photosensitive area is 4mm*4mm; the maximum size of the light source is 5mm*5mm; the vertical distance between the light-emitting surface of the light source and the probe board is 3mm–5mm; the tilt angle α of the emitting surface is ±1°; the distance from the chip edge to the via edge is 1.5mm–2mm; according to Figure 4 The embodiment shown yields the following: the shortest vertical distance between the reflecting surface and the wafer is 17.17 mm; the distance between the reflecting surface and the wafer is 22.17 mm to 32.17 mm; the distance from the center of the light source to the center of the via is 6.94 mm to 8.05 mm; and the distance from the center of the light source to the edge of the via is 3.44 mm to 4.55 mm.

[0078] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0079] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need further definition and explanation in subsequent figures. The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A light source device in a testing system, characterized in that, include: An optical mirror is used to reflect light. A light source, used to provide the light required for the test, wherein the light source has a light-emitting surface; A probe board is disposed below the light source, and the probe board has through holes; A wafer is disposed below the probe board, and the wafer has a chip photosensitive surface; The optical mirror and the wafer are at a certain angle in the horizontal direction; The vertical distance of the optical mirror relative to the wafer is obtained based on the difference in size between the chip's light-emitting surface and the via in the horizontal direction, the vertical distance of the probe board's upper surface relative to the chip's light-emitting surface, and the size of the light source. The horizontal position of the center of the light source relative to the center of the via is obtained based on the difference in size between the chip's light-emitting surface and the via in the horizontal direction, the vertical distance between the upper surface of the probe board and the chip's light-emitting surface, the size of the light source, and the vertical distance between the optical mirror and the wafer.

2. The light source device in the testing system as described in claim 1, characterized in that, The maximum horizontal distance between the center of the light source and the center of the through hole is determined by the horizontal dimensions of the through hole, the horizontal dimensions of the chip photosensitive surface, the distance from the lower surface of the optical mirror to the chip photosensitive surface in the vertical axis direction, the distance from the upper surface of the probe board to the light-emitting surface of the light source in the vertical direction, the thickness of the probe board, and the distance from the lower surface of the probe board to the chip photosensitive surface in the vertical direction.

3. The light source device in the testing system as described in claim 1, characterized in that, The minimum horizontal distance between the center of the light source and the center of the through hole is determined by the horizontal dimensions of the through hole, the horizontal dimensions of the chip photosensitive surface, the horizontal dimensions of the light source, the distance from the lower surface of the optical mirror to the chip photosensitive surface in the vertical axis direction, the distance from the upper surface of the probe board to the light-emitting surface of the light source in the vertical direction, the thickness of the probe board, and the distance from the lower surface of the probe board to the chip photosensitive surface in the vertical direction.

4. The light source device in the testing system as described in claim 1, characterized in that, The distance from the center of the light source to the edge of the through hole is not directly related to the horizontal dimension of the photosensitive surface of the chip.

5. The light source device in the testing system as described in claim 1, characterized in that, The light source is mounted on a separate PCB board.

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