TWI815913B - Cut wafer inspection device - Google Patents

Abstract

The present invention reliably detects defects such as cracks or chips hidden in the cutting lines of cut wafers, and shortens the inspection time of component wafers. The present invention is a device for inspecting the component area and peripheral area of a component wafer arranged on a diced wafer. It has a wafer holding part, an imaging part, a relative movement part, an inspection recipe registration part, and a control part. The control department has: Peripheral area inspection mode, which uses a specific imaging magnification to photograph the dicing line of the diced wafer along the dicing line, and inspects the peripheral area of the component wafer; and Component area inspection mode, which uses a lower shooting magnification than the shooting magnification in the peripheral area inspection mode to skip the wafer line and inspect the component area; and In the inspection recipe registration section, an inspection recipe for at least one of the execution component area inspection mode and the peripheral area inspection mode is registered.

Description

Cut wafer inspection device

The present invention relates to a diced wafer inspection device for inspecting a device area and a peripheral area of a device wafer on which a scribed or cut wafer is formed.

As an apparatus for cutting or grooving (scoring) a workpiece such as a wafer on which a semiconductor device or electronic component is formed, a die cutting apparatus is known (for example, Patent Documents 1 and 2).

Furthermore, a technology has been proposed that detects abnormalities in processing dimensions or processing status by photographing a workpiece during wafer cutting processing, and performs processing corresponding to the abnormal status (for example, Patent Document 2).

Furthermore, a technique is proposed, which involves photographing component wafers arranged on a wafer with scribed or cut wafers one by one, and inspecting the effective area (i.e., component area) and edge (i.e., peripheral area) of the component wafer (i.e., using inspection by an inspection device) (for example, Patent Document 3). [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. Sho 62-53804 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-253017 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-161236

[Problem to be solved by the invention]

In the technology disclosed in Patent Document 2, if you want to detect fine cracks (cracking), etc., you need to change the imaging magnification to a high magnification and suppress the moving speed of the wafer (that is, the cutting speed) to an unreasonable level. The degree to which it affects the quality of inspection.

On the other hand, there is a need to increase the number of wafers processed per unit time (so-called WPH) as much as possible. The inspection during wafer cutting is limited to measuring the position of the processing groove (notch) or the width of the notch, and large chips ( Defects), micro cracks, etc. are entrusted to a dedicated machine (i.e. inspection device).

However, in the inspection of the inspection device, there are both the device area where the device wafer is to be inspected with specific accuracy within a specific time, and the end portion of the wafer (that is, the peripheral area) where dicing lines (including scribe lines, the same applies below) are formed. If all divided areas are inspected at the same high magnification, the inspection time for one wafer will become longer. On the other hand, if you try to shorten the inspection time and inspect all divided areas at the same low magnification, there is a rule that defects such as fine cracks hidden in the wafer lines cannot be reliably detected. Therefore, an inspection device that can inspect both the component area and the surrounding area with specific accuracy within a specific time is required.

Therefore, the present invention was completed in view of the above-mentioned problems, and an object thereof is to provide a diced wafer inspection device that can reliably detect cracks or chips hidden in dicing lines on diced or diced wafers. Defects such as chips and film peeling can be eliminated, and the time to inspect the component area of the component chip can be shortened. [Technical means to solve problems]

In order to solve the above problems, one aspect of the present invention is a cut wafer inspection device. It is used to inspect the component area and surrounding area of the component chip arranged on the cut wafer. It is characterized by: a wafer holding portion that holds the wafer; An imaging unit that photographs a specific area set on the wafer at a specific imaging magnification; a relative moving part that moves the wafer and the imaging part relatively; The inspection recipe registration part registers the direction and speed of relative movement in the relative movement part, and the shooting magnification and shooting position in the imaging part as the inspection recipe; and a control part that controls the camera part and the relative movement part based on the inspection recipe; and The control department has: Peripheral area inspection mode, which uses a specific imaging magnification to photograph the dicing line of the diced wafer along the dicing line, and inspects the peripheral area of the component wafer; and Component area inspection mode, which uses a lower shooting magnification than the shooting magnification in the peripheral area inspection mode to skip the wafer line and inspect the component area; and In the inspection recipe registration section, an inspection recipe for at least one of the execution component area inspection mode and the peripheral area inspection mode is registered. [Effects of the invention]

According to the above-mentioned wafer inspection device, in the peripheral area inspection mode, the area along the wafer line (peripheral area) can be imaged with a high-magnification field of view, and defects such as cracks and chips can be reliably detected. On the other hand, in the component area inspection mode, the component area of the component wafer can be photographed with a relatively low magnification field of view size, thereby shortening the inspection time.

Hereinafter, modes for implementing the present invention will be described using the drawings.

Furthermore, in the following explanation, the three axes of the orthogonal coordinate system are represented as X, Y, and Z, the horizontal direction is represented as the Z direction. In addition, the Z direction represents the direction of resistance to gravity as upward, and the direction of gravity as downward. Also, let the direction of rotation with the Z direction as the central axis be the θ direction.

FIG. 1 is a schematic diagram showing the overall structure of an example of implementing the present invention. FIG. 1 shows a schematic diagram of the cut wafer inspection device 1 of the present invention.

The cut wafer inspection apparatus 1 inspects the device area Rc and the peripheral area Re of the device wafer C arranged on the cut wafer W. Furthermore, the component area Rc refers to the area where the main circuit of the component chip C is patterned. On the other hand, the peripheral area Re refers to an area arranged on the periphery (also called outside) of the element area Rc of the element wafer C, and is an area set to allow the positional deviation of the dicing line DL (also called Margin area, resection margin).

Furthermore, the peripheral region Re of the element wafer C is adjacent to the dicing line DL. Furthermore, the dicing line DL is a processing groove produced when scribing or cutting the wafer W. In actual condition, it is the space between the ridge lines of the processed wafer W. In this application, for convenience of explanation, the ridge line including the processed wafer W is called the dicing line DL.

Specifically, the diced wafer inspection apparatus 1 includes a wafer holding part 2, an imaging part 3, a relative movement part 4, an inspection recipe registration part 5, a control part 9, a computer CN, and the like.

The wafer holding part 2 holds the wafer W. For example, the cut wafer W uses a wafer ring R (also called a plane ring, a cut ring) and an extended sheet (not shown) to maintain the lower surface side. Specifically, the wafer holding part 2 maintains a horizontal state while supporting the wafer W from the lower surface side via the wafer ring R or the like. More specifically, the wafer holding unit 2 includes a wafer mounting table 20 with a horizontal upper surface.

The wafer mounting table 20 is provided with a groove portion or a hole portion at a portion in contact with a wafer ring holding the wafer W. The groove portion or hole portion is connected to a negative pressure generating device such as a vacuum pump through a switching valve or the like. Furthermore, the wafer holding part 2 can hold or release the wafer ring or the like by switching the groove parts or the hole parts to a negative pressure state or an atmosphere release state.

The imaging unit 3 photographs a specific area set on the wafer W at a specific imaging magnification. Specifically, the imaging unit 3 is configured to photograph the component region Rc and the peripheral region Re to be inspected, and is configured to switch the imaging magnification so that these regions can be photographed at an appropriate imaging magnification. Shoot. More specifically, the imaging unit 3 includes a lens barrel 30, an illumination unit 31, a half mirror 32, a plurality of objective lenses 33a and 33b, a rotator mechanism 34, a camera 35, and the like.

The lens barrel 30 fixes the lighting unit 31, the half mirror 32, the objective lenses 33a, 33b, the rotator mechanism 34, the camera 35, etc. in a specific posture to guide illumination light or observation light. The lens barrel 30 is attached to the device frame 1f via connecting metal fittings or the like (not shown).

The lighting unit 31 emits illumination light L1 required for photography. Specifically, the illumination unit 31 may include, for example, a laser diode, a metal halide lamp, a xenon lamp, LED (Light Emitting Diode, light emitting diode) lighting, or the like.

The half mirror 32 reflects the illumination light L1 emitted from the illumination unit 31 to the wafer W side, and allows the light (reflected light, scattered light) L2 incident from the wafer W side to pass through the camera 35 side.

The objective lenses 33a and 33b are used to form the image of the imaging area on the workpiece W on the camera 35 at different specific observation magnifications. The rotator mechanism 34 uses or switches any one of the objective lenses 33a and 33b. Specifically, the rotator mechanism 34 is one that rotates and stops in units of a specific angle based on manual or external signal control.

The camera 35 captures the imaging area F on the workpiece W to obtain an image. The acquired image is output to the outside as an image signal or image data (in the present invention, it is the chip position calculation unit described in detail below).

The relative movement unit 4 relatively moves the wafer holding unit 2 and the imaging unit 3 . Specifically, the relative movement unit 4 is configured with an X-axis slider 41 , a Y-axis slider 42 , and a rotation mechanism 43 .

The X-axis slider 41 is installed on the device frame 1f and allows the Y-axis slider 42 to move at any speed in the X direction and stop at any position. Specifically, the X-axis slider includes a pair of rails extending in the X direction, a slider portion that moves on the rails, and a slider driving portion that moves and stops the slider portion. The slide drive unit may be composed of a combination of a servo motor or a pulse motor that rotates and stops based on signal control from the control unit CN and a ball screw mechanism, or a linear motor mechanism. Moreover, the X-axis slider 41 is equipped with an encoder for detecting the current position or movement amount of the slider part. Examples of the encoder include a linear member with fine irregularities engraved at specific intervals called a linear scale, or a rotary encoder that detects the rotation angle of a motor that rotates a ball screw.

The Y-axis slider 42 moves the rotating mechanism 43 at any speed in the Y direction and stops at any position based on the control signal output from the control unit CN. Specifically, the Y-axis slider includes a pair of rails extending in the Y direction, a slider portion that moves on the rails, and a slider driving portion that moves and stops the slider portion. The slide drive unit may be composed of a combination of a servo motor or a pulse motor that rotates and stops based on signal control from the control unit CN and a ball screw mechanism, or a linear motor mechanism. Moreover, the Y-axis slider 42 is equipped with an encoder for detecting the current position or movement amount of the slider part. Examples of the encoder include a linear member with fine irregularities engraved at specific intervals called a linear scale, or a rotary encoder that detects the rotation angle of a motor that rotates a ball screw.

The rotation mechanism 43 rotates the wafer mounting table 20 in the θ direction at any speed and stops it at any angle. Specifically, the rotating mechanism 43 may be, for example, a direct drive motor or the like that is controlled by a signal from an external device to rotate/stationary to an arbitrary angle. The wafer mounting table 20 of the wafer holding part 2 is mounted on the member on the rotation side of the rotating mechanism 43 .

Since the relative movement unit 4 has such a structure, while holding the wafer W to be inspected, the wafer W can be opposed to the imaging unit 3 at a specific speed or angle in the XYθ direction, independently or in combination. Move, or stay still at any position or angle.

FIG. 2 is a perspective view of main parts showing an example of an embodiment of the present invention. FIG. 2 shows a situation in which the peripheral area Re of the device wafer C is sequentially photographed while the wafer W and the imaging unit 3 are relatively moved along the dicing line DL and the imaging area F is moved in the direction indicated by the arrow Vs. .

The inspection recipe registration unit 5 registers the direction and speed of relative movement in the relative movement unit 4 and the imaging magnification and imaging position in the imaging unit 3 as inspection recipes. Furthermore, in the inspection recipe registration section 5, inspection recipes related to the component area inspection mode and the peripheral area inspection mode described in detail below can be registered, and inspection recipes for executing both or at least one of these modes have been registered. Specifically, the inspection recipe registration unit 5 can photograph which location on the wafer W at which imaging magnification and in which order (i.e., imaging route T) in each of the component area inspection mode and the peripheral area inspection mode. , or how to set the moving speed and shooting interval or the moving distance and feeding speed at this time (also called recipe information) are registered as the inspection recipe for each inspection type.

The control unit 9 has, for example, the following functions or effects. ・Outputs a signal for holding/releasing the wafer W to the wafer holding unit 2 ・Control the rotator mechanism 34 to switch the objective lens (photography magnification) used ・Output shooting trigger to camera 35 ・Drive control of the relative moving unit 4: A function that monitors the current positions of the X-axis slider 41, the Y-axis slider 42, and the rotating mechanism 43 while outputting a driving signal ・Registration of shooting location or shooting route T, shooting interval (spacing, interval) ・Registration of check recipes and switching of used check recipes ・Inspection based on captured images

More specifically, the control unit 9 includes a computer CN or a programmable logic controller (ie, hardware), and an execution program thereof (ie, software). In addition, the inspection recipe registration unit 5 includes a part of the memory unit (register, memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc.) of the computer CN.

Furthermore, the control unit 9 controls the imaging unit 3 and the relative movement unit 4 based on the inspection recipe, and includes a device (such as a setting screen, etc.) and an execution device for setting operation modes called peripheral area inspection mode and component area inspection mode. (Computer CN and control machinery, etc.).

FIG. 3 is a conceptual diagram of an example of a mode for realizing the present invention. FIG. 3 illustrates an imaging route T or an imaging area F in the surrounding area inspection mode.

The peripheral area inspection mode refers to photographing one side of the cut wafer W including the dicing line DL at a specific imaging magnification (relatively high magnification) along the dicing line DL, and inspecting the component wafer C. Action pattern of surrounding area Re.

Specifically, in the peripheral area inspection mode, as shown in FIG. 3(a) , the imaging is performed along the imaging route T that relatively moves the imaging area F along the cutting line DL extending in the X direction. Next, As shown in FIG. 3(b) , the entire surface of the wafer W can be accurately captured while following the imaging path T that relatively moves the imaging area F along the dicing line DL extending in the Y direction. The surrounding area Re is inspected at a specific imaging magnification (relatively high magnification) to detect the extent of defects such as cracks or chips hidden in the wafer line DL.

More specifically, in the peripheral area inspection mode, an edge extraction process is performed to detect the chip end of the component chip C (i.e., the ridge), and check whether a part of the ridge does not enter the preset no-intrusion area and extends from the ridge. Whether cracks or debris, etc. do not enter the prohibited trespassing area, etc.

Furthermore, in the embodiment shown in FIG. 3 , the peripheral areas Re of a plurality of adjacently arranged component wafers are simultaneously photographed in a positional relationship across the dicing line DL, and are set in the inspection recipe registration unit 5 in this manner. Shooting magnification or shooting area F, shooting route T, etc.

FIG. 4 is a conceptual diagram of an example of a mode for realizing the present invention. FIG. 4 illustrates an imaging route T and an imaging area F in the component area inspection mode.

The component area inspection mode refers to an operation mode in which the imaging area F is relatively moved at a lower imaging magnification than the imaging magnification in the peripheral area inspection mode in such a manner as to skip the dicing line DL of the cut wafer W. The device region Rc of the device wafer C is inspected over the entire surface of the wafer W by photographing along the imaging path T.

Specifically, in the device area inspection mode, the device is inspected at a specific magnification (relatively low magnification) at a level that can determine whether foreign matter or damage has occurred on the device area Rc, or whether obvious pattern collapse or film formation failure has occurred. Photography and inspection of area Rc.

More specifically, in the device area inspection mode, an image (so-called teaching image) of a state in which foreign matter, damage, pattern collapse, or film formation failure does not occur on the device area Rc is pre-registered, and the teaching image is compared with the original image. This image of the device area Rc is taken for inspection to check whether foreign matter, damage, pattern collapse, film formation failure, etc. are generated in the device area Rc.

Furthermore, in the embodiment shown in FIG. 4 , the photography magnification or photography is set in the inspection recipe registration part 5 in such a way that the specific area photographed in the component area inspection mode skips the specific area photographed in the peripheral area inspection mode. Area F, shooting route T, etc.

FIG. 5 is a flow chart illustrating an example of a specific embodiment of the present invention. In FIG. 5 , the structure of photographing and inspecting the device area Rc and the peripheral area Re of the device wafer C arranged on the wafer W using the diced wafer inspection apparatus 1 is shown as a series of steps in each step.

First, the inspection recipe is set (step s11), and the inspection mode or sequence of the wafer W is determined. Next, the wafer W is placed on the wafer mounting table 20 of the diced wafer inspection device 1 (step s12), moved to the reading position of the reference mark (not shown) formed on the wafer W, and aligned. (step s13).

Then, based on the inspection recipe, the peripheral area inspection mode is switched (step s21), and the rotator mechanism 34 is rotated to select a high-magnification lens (step s22). Then, imaging and inspection are performed while relatively moving the imaging unit 3 and the relative movement unit 4 (step s23). It is determined whether all the shooting in this mode is completed (step s24). If not, the shooting and inspection are continued. If the shooting is completed, it is determined whether to execute another inspection mode (step s25).

Then, if another inspection mode (ie, component area inspection mode) is executed, the component area inspection mode is switched (step s31), and the rotator mechanism 34 is rotated to select a low-magnification lens (step s32). Then, imaging and inspection are performed while relatively moving the imaging unit 3 and the relative movement unit 4 (step s33). It is determined whether all the shooting in this mode is completed (step s34). If not, the shooting and inspection are continued. When the imaging is completed, the wafer W is extracted out of the apparatus (step s41). Furthermore, in the above-mentioned step s25, when other inspection modes are not executed, the wafer W is also extracted out of the device (step s41).

Then, it is determined whether to perform imaging and inspection of the next wafer W (step s42). When imaging and inspection are performed, the above steps s12 to s41 are repeated. On the other hand, when there is no photography or inspection to be performed, the inspection is terminated.

Furthermore, in the above, the following sequence is exemplified: first, the peripheral area inspection mode is executed, and then the component area inspection mode is executed. However, in order to embody the present invention, the order of the inspection modes may also be reversed. In addition, these inspection modes represent a series of action processes or states, and are not limited to the case of registration in the state explicitly stated in the inspection recipe, but also include cases where different shooting magnifications or shooting routes T, etc. are registered without being expressly stated.

Furthermore, the control unit 9 may output the shooting trigger to the imaging unit 3 in the following manner. ・While scanning relative movement in the X direction or Y direction, each time it moves a specific distance, it emits illumination light L1 for a very short time (so-called flash light). ・Or, a method of relatively moving and stationary to a specific position, and shooting with illumination light L1 in a stationary state (so-called step & repeat).

In addition, the shooting trigger means an image capture instruction for the camera 35 or an image processing device (not shown), an instruction for lighting the illumination light L1, etc. Specifically, as a shooting trigger, the flash device emits illumination light L1 during the time (so-called exposure time) when the camera 35 can take pictures (Example 1), or during the time when the illumination light L1 is irradiated (Example 2), Take the shot. Alternatively, the shooting trigger is not limited to an instruction to the camera 35, but may also be (Example 3) an image acquisition instruction to an image processing device that acquires an image. This can also correspond to the form of sequentially outputting image signals or image data from the camera 35 .

Since the diced wafer inspection device 1 of the present invention has such a structure, in the peripheral area inspection mode, the area along the dicing line (that is, the peripheral area Re) can be photographed with a high-magnification field of view size, thereby reliably Defects such as cracks or chips are easily detected (i.e. inspected). On the other hand, in the component area inspection mode, the component area Rc of the component wafer C can be photographed with a relatively low magnification field of view size, thereby shortening the inspection time. That is, the diced wafer inspection apparatus 1 can inspect both the device area Rc and the peripheral area Re with specific accuracy within a specific time.

[Other forms] Furthermore, in the above description, a configuration is exemplified in which the peripheral areas Rc of a plurality of adjacently arranged element wafers C are simultaneously imaged in a positional relationship across the dicing line DL, and in this way, the inspection recipe registration unit 5 Set the shooting magnification, shooting area F, shooting route T, etc.

Such a configuration is preferable because the number of shots can be reduced and the inspection time required for each wafer W can be shortened.

However, when the width of the cutting line DL is relatively large relative to the imaging area F, and the ridge lines in the peripheral area Re easily exceed the field of view, or when the cracks or defects to be detected are small and the imaging magnification is increased, it is not possible to use the same method horizontally. When simultaneously photographing the positional relationship across the dicing line DL, the peripheral area Rc of one element wafer C may be photographed.

1: Cut wafer inspection device 1f:Device frame 2: Wafer holding part 3:Camera Department 4: Relative movement part 5: Check the recipe login section 9:Control Department 20:Wafer mounting table 30: Lens tube 31:Lighting Department 32: Half mirror 33a:Objective lens 33b:Objective lens 34:Rotator mechanism 35:Camera 41:X-axis slider 42: Y-axis slider 43: Rotating mechanism C: component chip CN:Control Department DL: Cutting line (slot/gap) F: Shooting area (field of view) L1: illumination light L2: Light incident from the wafer side (reflected light, scattered light) R:wafer ring Rc: component area Re: Surrounding area (near the ridge) T:shooting route W:wafer

FIG. 1 is a schematic diagram showing the overall structure of an example of implementing the present invention. FIG. 2 is a perspective view of main parts showing an example of an embodiment of the present invention. 3(a) and (b) are conceptual diagrams of an example of a mode for realizing the present invention. FIG. 4 is a conceptual diagram of an example of a mode for realizing the present invention. FIG. 5 is a flowchart of an example of implementing the present invention.

3:Camera Department

35:Camera

C: component chip

DL: Cutting line (slot/gap)

F: Shooting area (field of view)

Rc: component area

Re: Surrounding area (near the ridge)

W:wafer

Claims (2)

A cut wafer inspection device that inspects the component area and surrounding area of a component wafer arranged on a cut wafer, and is characterized by having: a wafer holding part that holds the above-mentioned wafer; An imaging unit that photographs a specific area set on the wafer at a specific imaging magnification; a relative movement unit that relatively moves the wafer and the imaging unit; An inspection recipe registration unit that registers the direction and speed of relative movement in the relative movement unit and the photography magnification and photography position in the imaging unit as an inspection recipe; and a control unit that controls the imaging unit and the relative movement unit based on the inspection recipe; and The above control department has: A peripheral area inspection mode, which uses a specific imaging magnification to photograph the wafer line along the wafer line in a manner that includes the wafer line, and inspects the peripheral area of the device wafer; and A component area inspection mode that uses a lower shooting magnification than the shooting magnification in the peripheral area inspection mode to skip the cutting line and inspect the component area; and In the inspection recipe registration section, the inspection recipe for executing at least one of the component area inspection mode and the peripheral area inspection mode is registered. Such as the cut wafer inspection device of claim 1, wherein For the above inspection recipe registration part, set it as follows: The peripheral areas of the plurality of adjacent device wafers are simultaneously photographed in a positional relationship across the dicing line.