A kind of detection method of pixel performanceTechnical field
The present invention relates to image sensor technologies fields, and in particular to a kind of detection method of pixel performance.
Background technology
Image sensor chip is that electronic equipment obtains information " eyes ", it has also become electronic terminal product is indispensableStandard configuration.It has been shown that, the year two thousand twenty cmos image sensing are reported according to " the cmos image sensor industry condition " of market survey companyThe operating income in device (CIS) market will rise to 16,000,000,000 dollars, and Compound Annual Growth Rate is more than 11%, cmos image sensorAlready become imaging sensor or even integrated circuit fields receive the product gazed at.With the hair of cmos image sensor technologyExhibition, following CIS markets will obtain further should in fields such as consumer electronics, wearable device, monitoring security protection, artificial intelligenceWith with lasting growth.
Cmos image sensor species is various, divides from pixel resolution, there is 300,000,1,000,000,5,000,000,12,000,000 etc.,Divide from chip size, there is 1/6 inch, 1/4 inch, 1/2 inch, APS-C etc..In addition, also many parameter measure images passThe pixel qualities or picture quality of sensor, as shown in Table 1.
Table one：
But since parameter is various and strongly professional, it is generally difficult to differentiate the performance of CIS pixels by parameter.And meshIt is preceding also numerous various parameters seldom to be united there are one index.
The content of the invention
In order to overcome problem above, the present invention is intended to provide a kind of can be convenient to the unified detection method of pixel performanceThe quality of user's perpendicular evaluation cmos image sensor.
In order to achieve the above object, the present invention provides a kind of detection method of pixel performance, including：
Step 01：The parameter of the pixel in different process stage is obtained respectively；The parameter includes：Sensitivity, dark current, quantumEfficiency, signal-to-noise ratio, dynamic range and each Pixel Dimensions；The pixel in the different process stage includes preceding illuminated pixel techniqueThe pixel in stage, the pixel of back-illuminated type pixel operation stage and 3D stack the pixel of pixel operation stage；
Step 02：One integrated performance index is calculated according to the parameter；Wherein, the integrated performance index is calculated to adoptFormula is：
Wherein, QE is quantum efficiency, and Sensitivity is sensitivity, DR is dynamic range, SNR is signal-to-noise ratio, DC is dark electricityStream, Pixel_Size are Pixel Dimensions；
Step 03：Pixel performance quality is judged according to integrated performance index；Wherein, the higher expression pixel of integrated performance indexPerformance is better.
Preferably, the dynamic range includes maximum output voltage and reads noise, the signal-to-noise ratio by full well charge andThe influence of Noise Background.
Preferably, the dynamic range is directly proportional to output voltage, is in inverse ratio with reading noise.
Preferably, the signal-to-noise ratio and full well charge are proportional, are in inverse ratio with Noise Background.
Preferably, the pixel includes roller pixel and/or global pixel.
Preferably, the pixel is image sensor pixel.
The detection method of the pixel of the present invention, it is by setting integrated performance index, each important parameter of pixel is unifiedReflect in integrated performance index, the quality of pixel can be monitored using integrated performance index, pixel resolutionJust, detection efficiency is improved.
Description of the drawings
Fig. 1 is the flow diagram of the detection method of the pixel performance of the preferred embodiment of the present invention
Fig. 2 is that the development obtained using the typical roller pixel of FOM values characterization of the preferred embodiment of the present invention is becomeGesture schematic diagram
Fig. 3 is that the development obtained using the typical global pixel of FOM values characterization of the preferred embodiment of the present invention is becomeGesture schematic diagram
Specific embodiment
To make present disclosure more clear and easy to understand, below in conjunction with Figure of description, present disclosure is made into oneWalk explanation.Certainly the invention is not limited to the specific embodiment, the general replacement known to those skilled in the artCover within the scope of the present invention.
The present invention is described in further detail below in conjunction with attached drawing 1-3 and specific embodiment.It should be noted that attached drawing is equalUsing very simplified form, using non-accurate ratio, and only to it is convenient, clearly reach and aid in illustrating the present embodimentPurpose.
Referring to Fig. 1, the detection method of the pixel performance of the present embodiment includes：
Step 01：The parameter of the pixel in different process stage is obtained respectively；The parameter includes：Sensitivity, dark current, quantumEfficiency, signal-to-noise ratio, dynamic range and each Pixel Dimensions；
Specifically, the pixel in different process stage includes pixel, the back-illuminated type pixel in preceding illuminated pixel technique (FSI) stageThe pixel and 3D in technique (BSI) stage stack the pixel in technique (3D Stacked) stage；Pixel further include roller pixel and/orGlobal pixel, the pixel of the present embodiment is image sensor pixel.
Step 02：One integrated performance index is calculated according to parameter；Wherein, the integrated performance index and quantum efficiency,Sensitivity, dynamic range, signal-to-noise ratio are proportional, are in inverse ratio with dark current, Pixel Dimensions；
Specifically, the integrated performance index of the present embodiment and the relation of parameter show as formula：
Wherein, FOM is integrated performance index, and QE is quantum efficiency, and Sensitivity is sensitivity, DR is dynamic range, SNRFor signal-to-noise ratio, DC be dark current, Pixel_Size is Pixel Dimensions；Dynamic range includes maximum output voltage and reads noise,Signal-to-noise ratio includes full well charge (full well charge) and Noise Background (noise floor)；Dynamic range and output electricityDirect ratio is pressed into, is in inverse ratio with reading noise；Signal-to-noise ratio and full well charge are proportional, are in inverse ratio with noise floor.
Such as table two, the relation of the integrated performance index of the present embodiment and each parameter can represent as follows：
Table two：
In table two, represent to increase to upward arrow, down arrow represents to reduce.
Step 03：Pixel performance quality is judged according to integrated performance index.
Specifically, with reference to the formula of integrated performance index, the pixel that FOM is reflected can be intuitively evaluated from table twoQuality, FOM is higher, and pixel is better, and pixel resolution is higher.For example, Pixel Dimensions are smaller, FOM is higher, represents that pixel is got overGood, pixel resolution is higher.The development trend of this and present pixel technique is consistent.Set synthesis through this embodimentPerformance indicator, can realize the integration to the parameters of pixel and uniformly to appear as an index good to monitor the quality of pixelIt is bad.
Referring to Fig. 2, for roller pixel, in FSI, BSI and 3D Stacked three phases, Pixel Dimensions it is bigSmall and FOM proportional relation of size.Referring to Fig. 3, for global pixel, in FSI, BSI and 3D Stacked tri-Stage, the size of Pixel Dimensions and the size of FOM also proportional relation.
Table three is referred to, wherein, Rolling Shutter are roller pixel, and Global Shutter are global pixel, tableRoller pixel and the global parameters of pixel and the relation of FOM indexs are listed in three, visual and clear can be seen,FOM indexs can relatively accurately reflect the quality of pixel.Therefore, the detection method of the pixel of the present embodiment passes through settingFOM indexs reflect each important parameter of pixel is unified into FOM indexs, and picture can be monitored using a FOM indexThe quality of element, the height of pixel resolution improve detection efficiency.
Table three：
Although the present invention is disclosed as above with preferred embodiment, the right embodiment illustrate only for the purposes of explanation and, the present invention is not limited to, if those skilled in the art can make without departing from the spirit and scope of the present inventionDry changes and retouches, and the protection domain that the present invention is advocated should be subject to described in claims.