Selection device and method of integrated circuit chip

Abstract

To determine deposition failure of an integrated circuit chip such as an LCOS element non-destructively.SOLUTION: In selecting an integrated circuit chip (11) which comprises a thin film like SiO2 film deposited on a large number of elements such as pixel electrodes, light emitting parts 51, 53 irradiate the thin film with light of at least two wavelengths such as 455 nm and 610 nm, measurement parts 54, 56 measure the reflection coefficent of the light, a calculation unit 57 calculates a difference of the reflection coefficient, and a determination unit 58 determines to be nondefective when the difference of the reflection coefficient is below a threshold value and determines to be defective when the difference of the reflection coefficient is equal to or greater than the threshold value. Therefore, the deposition failure of the thin film in the integrated circuit chip that appears as luminance unevenness in the case of the LCOS element can be determined non-destructively and can be selected before the chip with thin film thickness is inputted into a process, especially even on the element surface.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an apparatus and method suitable for sorting integrated circuit chips, particularly LCOS (Liquid Crystal on Silicon) elements. [Background technology]

[0002] The LCOS element has a higher aperture ratio and higher resolution than a transmissive liquid crystal element, and is therefore used in projectors and rear projection televisions. In this LCOS element, liquid crystal is filled between a pixel electrode formed on a silicon chip and a glass substrate on which an opposing electrode is formed, and the liquid crystal adjusts the reflection of incident light at a reflective film formed on the pixel electrode, thereby displaying an image. The reflective film is, for example, a pixel electrode made of an Al film, which also functions as a reflective film, and a high-reflection film made of a SiO2 film and a SiN film laminated on the pixel electrode. The pixel electrode and the high-reflection film work together to function as the reflective film. In the present invention, it is sufficient that a thin film is formed on an element such as a pixel electrode, and the combination of a reflective film and a high-reflection film is not necessarily required.

[0003] Therefore, in this LCOS element, the surface of the reflective film needs to be formed to be smooth. However, since the reflective film is formed on the individually separated pixel electrodes, unevenness (unevenness in film thickness) occurs between the pixel electrodes and on the pixel electrodes. When an image is displayed, this unevenness (unevenness in film thickness) causes uneven brightness, for example, when light that should be reflected forward is reflected to the side. For this reason, after the reflective film is formed, a planarization process is performed using CMP (chemical mechanical polishing).

[0004] However, CMP has a tendency that the polishing speed increases as the pattern density of the polished area becomes coarser, which is called the microloading effect. The polishing speed is faster in the peripheral area where the pattern density is coarser than in the pixel electrode area. In particular, the corners are polished too much, resulting in uneven brightness. Therefore, it is desirable to measure the remaining amount of the reflective film after polishing to select the chips, but this is difficult to measure in the area where the pattern (pixel electrode) is present.

[0005] On the other hand, since it is difficult to monitor the amount of polishing during CMP, currently, when performing the above-mentioned CMP on a wafer before chips are cut out, the time is measured, and the remaining film amount is measured in the portion of the pattern where the film thickness can be measured on the processed wafer and reflected in the processing of the next wafer. However, there are variations depending on the wafer, and the chip sorting work is required.

[0006] Patent Document 1 is a transmissive liquid crystal display device, which judges whether the cell pattern is good or bad and seals defective products with a liquid other than liquid crystal, thereby eliminating waste of liquid crystal and minimizing the impact on subsequent processes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2006-300979 A Summary of the Invention [Problem to be solved by the invention]

[0008] Although Patent Document 1 judges the quality of liquid crystal display devices, it is a transmissive liquid crystal display device, does not include processes such as CMP, and is merely a type of wafer test (a test to determine whether a circuit pattern is formed correctly), and is unable to judge film formation defects in integrated circuit chips, such as the above-mentioned brightness unevenness.

[0009] An object of the present invention is to provide an apparatus and method for screening integrated circuit chips that are capable of determining film formation defects. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the integrated circuit chip sorting device and method of the present invention are device and method for sorting integrated circuit chips consisting of a thin film formed on the surface of a plurality of arranged elements, and are characterized in that they include an emission means for irradiating the thin film with light of at least two predetermined wavelengths which are different from each other, a measurement means for measuring the reflectance of the light of the at least two wavelengths from the thin film, a calculation means for calculating the difference between the reflectances measured by the measurement means, and a judgment means for judging the chip as a good product if the difference in reflectance calculated by the calculation means is less than a predetermined threshold value, and judging the chip as a defective product if the difference in reflectance calculated by the calculation means is equal to or greater than the threshold value. Effect of the Invention

[0011] According to the integrated circuit chip sorting device and method of the present invention, thin film deposition defects in integrated circuit chips, which appear as brightness unevenness in the case of LCOS elements, can be determined non-destructively, particularly on the surface of the element, and chips with thin film thickness can be sorted out before they are put into processing. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a schematic configuration of an integrated circuit chip inspection device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic structure of an LCOS element as an example of an integrated circuit chip on which the test shown in FIG. 1 is performed. [Diagram 3] 3 is a graph showing the results of measurements made by the inventor of the present application regarding the relationship between the film thickness and the reflectance of a SiO 2 film when a short-wavelength light of 455 nm is irradiated on an LCOS element as shown in FIG. 2. [Figure 4] 3 is a graph showing the results of measurements by the inventors of the spectral characteristics of an LCOS element as shown in FIG. 2. [Diagram 5]3 is a graph showing the measurement results by the inventor of the present application, illustrating the defective product determination rate versus the difference in reflectance when an LCOS element as shown in FIG. 2 is irradiated with light having wavelengths of 455 nm and 610 nm. [Figure 6] 2 is a functional block diagram showing in detail a reflectance measuring section in the inspection device of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Next, the present embodiment will be described with reference to the drawings. In the description of the drawings described below, the same or similar parts are given the same or similar reference numerals. However, it should be noted that the drawings are schematic and may differ from the actual ones. In addition, the embodiments shown below are examples of devices and methods for embodying technical ideas, and do not specify the material, shape, structure, arrangement, etc. of each component part. Various modifications can be made to the present embodiment within the scope of the claims.

[0014] Fig. 1 is a block diagram showing a schematic configuration of an integrated circuit chip inspection device according to an embodiment of the present invention. The inspection in Fig. 1 is an inspection of integrated circuit chips, and is performed before assembly into LCOS elements, etc., which will be described later. Wafers on which multiple integrated circuit chips are formed are received one by one in a receiving section S1. Next, a visual inspection is performed on each chip in a visual inspection section S2 using a predetermined illumination light, an imaging device, etc. If the visual inspection section S2 determines that a chip is defective due to poor pattern formation, dust adhesion, etc., the defective product is processed in a defect processing section S3, such as by marking.

[0015] For chips that pass the visual inspection section S2, a probe is applied in the probe test section S4 to perform a functional test of the integrated circuit. Then, a reflectance measurement section S5, which is newly implemented in this embodiment, performs a reflectance measurement. The order of the probe test section S4 and the reflectance measurement section S5 may be reversed, and both perform tests and measurements on all chips that pass the visual inspection section S2. The test and measurement results in the probe test section S4 and the reflectance measurement section S5 are integrated in the data integration section S6, and after dicing into individual chips, the chips that are judged as good products in all tests are sorted into good product trays by a chip sorter in the good product judgment section S7 and sent to the post-process. In the post-process, the final assembly into an LCOS element is performed, such as forming a peripheral wall with a sealant, bonding the opposing glass substrate, and sealing in liquid crystal. In the data integration section S6, chips that are judged as bad products in any test are sorted into bad product trays by a chip sorter in the bad product processing section S8 and disposed of.

[0016] FIG. 2 is a cross-sectional view showing a schematic structure of the LCOS element 1, which is an example of an integrated circuit chip to be inspected as shown in FIG. 1. In the LCOS element 1, liquid crystal is filled between a large number of pixel electrodes 12 formed on a silicon chip 11 and a glass substrate on which a counter electrode (not shown) is formed, and the liquid crystal adjusts the reflection of incident light at a reflective film formed on the pixel electrodes 12 to display an image. A switching element (driving the pixel electrodes 12) and the like are formed below the pixel electrodes 12, so that the LCOS element 1 has a high aperture ratio. The counter electrode is formed of a transparent electrode. In this embodiment, the pixel electrodes 12 are made of an Al film and also function as a reflective film. A thin-film high-reflection film 13 made of a SiO2 film 14 on the lower layer side and a SiN film 15 on the surface side is laminated on the pixel electrodes 12, which are the reflective film. The pixel electrodes 12 and the high-reflection film 13 work together to form a reflective film. With respect to the film thickness, for example, the SiO2 film 14 is 300 to 350 Å, and the SiN film 15 is 1000 to 1200 Å on the pixel region 16 where the pixel electrode 12 is formed.

[0017] As described above, in this LCOS element 1, unevenness (unevenness in film thickness) occurs in the reflective film 13 between the spaces 17 of the pixel electrodes 12 and on the pixel electrodes 12, so the LCOS element 1 is subjected to a planarization process by CMP before being accepted by the accepting section S1 in Fig. 1. However, in the pixel region 16 which appears to have a regular lattice shape when viewed enlarged, it may appear rainbow-colored, i.e., slight unevenness in brightness may occur even after the CMP process. For this reason, in the inspection in Fig. 1, reflectance measurement is performed in the reflectance measuring section S5 which is newly added in this embodiment.

[0018] This is based on the inventor's knowledge that the spectral characteristics of an integrated circuit chip tend to have higher reflectance at short wavelengths as the thickness of the SiO2 film 14 becomes thinner. Fig. 3 is a graph showing the relationship between the thickness and reflectance of the SiO2 film 14 when a specific portion, specifically the center of the pixel electrode 12 at the center of the pixel region 16, is irradiated with blue light of a short wavelength, specifically 455 nm. From this graph, it can be seen that there is a correlation between the thickness and the reflectance, and that in this LCOS element 1, where it is difficult to measure the thickness on the actual pixel region 16, it is possible to estimate the thickness from the reflectance.

[0019] Meanwhile, Fig. 4 is a graph showing the above-mentioned spectral characteristics in detail. Samples α1, α2, and α3 are different lots, and the thicknesses of the SiO2 film 14 measured are 42.2 Å, 251.2 Å, and 509.8 Å, respectively. Looking at the aforementioned 455 nm vicinity in Fig. 4, the reflectance of the thin sample α1 is certainly higher than that of the thick samples α2 and α3. However, the thick samples α2 and α3 tend to have an increased reflectance on the very short wavelength (400 nm) side, and in particular the thickest sample α3 has a reflectance of about 80%, which is close to that of the thin sample α1.

[0020] Therefore, in this embodiment, the wavelength used in the reflectance measurement unit S5 is first set to the short wavelength of 455 nm. Next, the opposite long wavelength of 610 nm red light is used. What is noteworthy is that in this embodiment, the difference in reflectance between these two lights is obtained (the reflectance at 610 nm is subtracted from the reflectance at 455 nm). In the reflectance measurement unit S5, if the difference is less than a predetermined threshold, the product is judged as a good product in the quality judgment unit S7, and if the difference is equal to or greater than the threshold, the product is judged as a defective product in the defect processing unit S8. Specifically, in this embodiment, the threshold is set to 5%.

[0021] FIG. 5 is a graph showing the defective product determination rate for the result (difference) of subtracting the reflectance at 610 nm from the reflectance at 455 nm. The vertical axis is the defective product determination rate due to luminance unevenness. The horizontal axis is the result (difference) of subtracting the reflectance at 610 nm from the reflectance at 455 nm. If the reflectance at 455 nm is larger than the reflectance at 610 nm, it is +, and if it is smaller, it is -. According to FIG. 5, if the difference is -, the defective product determination rate is 0%, and if the difference is +, a defective product due to luminance unevenness occurs. And, if the difference is 5%, the defective product determination rate is 20%, so by setting the threshold for defective product determination to this 5%, it is possible to appropriately determine defective products. If the difference exceeds 15%, it is almost defective. Also, by using light with a wavelength of 455 nm and light with a wavelength of 610 nm, the thickness (excessive scraping) of the SiO2 film 14 can be effectively determined.

[0022] FIG. 6 is a functional block diagram showing the reflectance measurement unit S5 of FIG. 1 in detail. The reflectance measurement unit S5 of this embodiment includes three light-emitting units 51, 52, and 53, each having a wavelength of 455 nm, 610 nm, and a green light of 550 nm. These light-emitting units 51, 52, and 53 can be obtained by selecting the wavelength of white light. The light from each light-emitting unit 51, 52, and 53 is irradiated onto the center of the pixel electrode 12 of the representative pixel in the center of the pixel region 16 of the chip of each LCOS element 1. The reflected light is incident on each of the measuring units 54, 55, and 56, and the reflectance is calculated by dividing the amount of light received by the amount of light from the light-emitting units 51, 52, and 53. For this reflectance calculation, a part of the light from the light-emitting units 51, 52, and 53 may be directly incident on the measuring units 54, 55, and 56.

[0023] Thereafter, the difference in reflectance measured by measuring units 54, 56 is calculated by calculation unit 57 and compared with the threshold value of 5% by judgment unit 58 to judge whether the product is good or bad. In this way, defects in the formation of the uniform and smooth thin film (14) on the integrated circuit chip, which appear as uneven brightness in the case of LCOS element 1, can be judged non-destructively even on the surface of the element (12), in particular, and chips with thin film thickness can be selected before being put into the process.

[0024] On the other hand, the reflectance measuring section S5 in Fig. 6 is provided with a 550 nm light emitting section 52 and a measuring section 55. The judging section 58 judges whether the reflectance of the LCOS element 1 judged as a non-defective product is equal to or greater than a predetermined threshold value for each of the colors of 455 nm (B), 550 nm (G), and 610 nm (R), and selects which color element is to be used as the LCOS element with a reflectance equal to or greater than the threshold value. Specifically, for example, if the threshold value of the reflectance of RGB is uniformly set to 90%, an element of a color that is equal to or greater than 90% is selected. If there are multiple colors that are equal to or greater than the threshold value, the element of the color with the lowest yield rate may be selected, or the color with the highest reflectance may be selected.

[0025] In this way, it is possible to judge the quality of the integrated circuit chip and, in parallel, to select the color when used as an LCOS element. The light emitting units 51, 52, 53 and the corresponding measuring units 54, 55, 56 irradiate and measure light of wavelength components corresponding to the three primary colors R, G, and B, respectively. The wavelength components of the respective colors R, G, and B are, for example, 430 to 470 nm, 500 to 570 nm, and 590 to 750 nm.

[0026] The technical ideas that can be understood from this disclosure are described below.

[0027] The integrated circuit chip sorting device disclosed herein is an apparatus for sorting integrated circuit chips each having a smooth thin film formed on the surface of a plurality of arranged elements, and is characterized by comprising an emitting means for irradiating the thin film on the elements with light of at least two predetermined wavelengths which are different from each other, a measuring means for measuring the reflectance of the light of the at least two wavelengths from the thin film on the elements, a calculating means for calculating the difference between the reflectances measured by the measuring means, and a judging means for judging a product as good if the difference in reflectance calculated by the calculating means is less than a predetermined threshold value, and for judging a product as defective if the difference in reflectance calculated by the calculating means is equal to or greater than the threshold value.

[0028] In addition, the sorting method for integrated circuit chips disclosed herein is a method for sorting integrated circuit chips having a smooth thin film formed on the surface of a plurality of arranged elements, and is characterized by including an irradiation step of irradiating the thin film on the elements with light of at least two predetermined wavelengths that are different from each other, a measurement step of measuring the reflectance of the light of the at least two wavelengths from the thin film on the elements in the irradiation step, a calculation step of calculating the difference between the reflectances measured in the measurement step, and a judgment step of judging the chip as a good product if the difference in reflectance calculated in the calculation step is less than a predetermined threshold, and judging the chip as a defective product if the difference in reflectance calculated in the calculation step is equal to or greater than the threshold.

[0029] According to the above configuration, when selecting an integrated circuit chip in which a relatively uniform and smooth thin film is formed on the surface of a plurality of arranged elements such as LCOS elements, the present disclosure utilizes the properties of the thin film that should be formed uniformly. As the properties of the thin film, for example, a SiO2 film has a spectral characteristic in which the reflectance at a short wavelength increases as the film becomes thinner. Therefore, when the light emitting means (irradiation step) irradiates light of at least two predetermined wavelengths different from each other onto the thin film on the element, and the reflectance at a long wavelength is subtracted from the reflectance at a short wavelength, if the thickness of the thin film is appropriate, the difference is small, whereas if the thickness is thin, the reflectance at a short wavelength increases as described above, and the difference in reflectance at the two wavelengths increases. Therefore, the measuring means (step) measures the reflectance of at least two wavelengths of light, and the calculation means (step) calculates the difference in reflectance, and the judging means (step) can judge the product as a non-defective product if the difference in reflectance is less than a predetermined threshold, and can judge the product as a defective product if the difference in reflectance is equal to or greater than the threshold.

[0030] In this way, defects in the formation of uniform and smooth thin films on integrated circuit chips, which appear as uneven brightness in the case of LCOS elements, can be determined non-destructively, especially on the surface of the element, and chips with thin film thicknesses can be selected before they are put into processing.

[0031] Furthermore, in the integrated circuit chip sorting device of the present disclosure, the integrated circuit chips are LCOS elements, and the smooth thin film is a SiO2 film.

[0032] According to the above configuration, the LCOS element, which is the display device, requires that a uniform and smooth SiO2 film be formed on a large number of elements as part (layer) of the reflective film, and furthermore, due to the above-mentioned spectral characteristics of the SiO2 film, the reflectance at short wavelengths tends to increase as the film thickness decreases.

[0033] Therefore, it is preferable to apply the integrated circuit chip sorting device of the present disclosure to determine the quality of the SiO2 film of an LCOS element.

[0034] In addition, in the integrated circuit chip sorting device of the present disclosure, the SiO2 film is polished to the smooth thin film by CMP.

[0035] According to the above configuration, when polishing by CMP, it is not possible to monitor the amount of chips being polished with an abrasive, and excessive polishing will result in uneven brightness in the LCOS elements, so it is preferable to apply the non-destructive integrated circuit chip sorting device of the present disclosure after polishing.

[0036] In the integrated circuit chip sorting device of the present disclosure, the light emitting means emits light having wavelengths of 455 nm and 610 nm.

[0037] According to the above configuration, as described above, the thinner the SiO2 film, the higher the reflectance at short wavelengths. Therefore, by using blue light with a wavelength of 455 nm and red light with an opposite long wavelength of 610 nm, the thickness (excessive cutting) of the SiO2 film can be effectively determined.

[0038] Furthermore, in the integrated circuit chip sorting device of the present disclosure, the determining means determines a chip as defective when the difference in reflectance calculated by the calculating means is 5% or more.

[0039] According to the above configuration, when the reflectance of 610 nm red light is subtracted from the reflectance of 455 nm blue light on a SiO2 film, if the difference in reflectance is 0% or more, brightness unevenness occurs, and if it is 5% or more, the brightness unevenness reaches 20%. Therefore, when the 455 nm blue light and the 610 nm red light are used on the SiO2 film, the allowable difference in reflectance between them is set to 5%, so that defective products can be appropriately determined.

[0040] In addition, in the integrated circuit chip sorting device disclosed herein, the light emitting means further emits light with a wavelength of 550 nm, the measuring means measures the reflectance of each of the three wavelengths of light, and the judging means judges whether the measurement results measured by the measuring means for the integrated circuit chip judged to be a good product have a reflectance equal to or greater than a predetermined threshold value for each of the RGB LCOS elements, and selects the color when used as an LCOS element.

[0041] According to the above configuration, in the case of an LCOS element, the light emitting means emits blue light with a wavelength of 455 nm and red light with a wavelength of 610 nm, and the calculation means calculates the difference between the reflectance measured by the measurement means, and the judgment means judges whether the element is good or bad. The light emitting means further emits a third green light with a wavelength of 550 nm, and the measurement means also measures the reflectance of the green light. Then, for the integrated circuit chip judged to be good, the judgment means compares the reflectance of each of the RGB colors with a threshold value set for each color, and selects which color element to use as the LCOS element with a reflectance equal to or higher than the threshold. Specifically, for example, if the threshold value of the RGB reflectance is uniformly set to 90%, the element with the color equal to or higher than 90% is selected. If there are multiple colors equal to or higher than the threshold, the element with the lowest quality rate may be selected, or the color with the highest reflectance may be selected.

[0042] Therefore, it is possible to judge the quality of the integrated circuit chip (in parallel) and also to select the color when used as an LCOS element.

[0043] The present invention can be implemented if there is data on film thickness and reflectance, and can be implemented to sort not only LCOS elements, but also integrated circuit chips consisting of a thin film formed on the surface of a plurality of arranged elements. [Explanation of symbols]

[0044] 1 LCOS element 11 Silicon chip 12 Pixel electrode 13 Highly reflective coating 14 SiO2 film 15 SiN film 16 pixel area 17 hours 51, 52, 53 Light emitting part 54, 55, 56 Measurement section 57 Calculation section 58 Judgment section S1 Reception Department S2 Visual Inspection Department S3 Defect handling section S4 Probe Test Unit S5 Reflectance measurement section S6 Data Integration Department S7 Good product judgment section S8 Defect handling section

Claims

1. An apparatus for selecting integrated circuit chips each having a thin film formed on the surface of a plurality of arranged elements, comprising: A light emitting means for irradiating the thin film with light having at least two predetermined wavelengths different from each other; a measuring means for measuring the reflectance of light of at least two wavelengths from the thin film; A calculation means for calculating a difference in reflectance measured by the measurement means; and determining means for determining a non-defective product when the difference in reflectance calculated by said calculating means is less than a predetermined threshold, and for determining a defective product when the difference in reflectance calculated by said calculating means is equal to or greater than the threshold.

2. 2. The integrated circuit chip sorting apparatus according to claim 1, wherein said integrated circuit chip is an LCD device.

3. the light emitting means irradiates the thin film with light having wavelength components corresponding to the three primary colors of RGB, the measuring means measures the reflectance of each of the wavelength components of the three primary colors, The integrated circuit chip sorting device according to claim 2, characterized in that the judgment means judges whether the measurement results measured by the measurement means for the integrated circuit chip judged to be a non-defective product have a reflectance equal to or greater than a predetermined threshold value for each of the RGB LCOS elements, and selects a color when used as an LCOS element.

4. A method for selecting integrated circuit chips having a thin film formed on a surface of a plurality of arranged elements, comprising the steps of: an irradiation step of irradiating the thin film with light having at least two predetermined wavelengths different from each other; a measuring step of measuring reflectances of light of at least two wavelengths from the thin film in the irradiating step; A calculation step of calculating a difference between the reflectances measured in the measurement step; a determining step of determining an integrated circuit chip as non-defective if the difference in reflectance calculated in the calculating step is less than a predetermined threshold, and determining an integrated circuit chip as defective if the difference is equal to or greater than the threshold.

Images