TW418542B - Color CMOS imager with multiple photodiodes - Google Patents

Abstract

This invention is about a kind of color CMOS imager with multiple photodiodes, in which different photodiodes are manufactured for different color unit cells such that the photodiode of each color unit cell individually has different PN junction depth according to the difference of visible light sensed. Additionally, the defect caused by implantation can be reduced and the sensitivity of light can be raised. Furthermore, during the fabrication, the photodiode that only has the optimum sensing for a specific wavelength of visible light among different colors can be fabricated so as to increase the performance of the color CMOS imager.

Description

418542418542

本發明係有關於一種影像感測器’特別是有關於一種 具有多樣感光二極體之彩色金氧半影像感測器。The present invention relates to an image sensor ', and more particularly to a color metal-oxide-semiconductor image sensor with various photodiodes.

就感光二極體（photodiode)而言，主要是利用矽之PN 接合面，將入射光線之強度轉換為光電流。基本上將複 數個感光二極體，設置成感光二極體陣列（ph〇t〇di〇de array)，即可以作為影像感測器，例如金氧半影像感測器 (CMOS Imager)。 就傳統之金氧半影像感測器而言，無論是彩色或是黑 白’所使用之感光二極體均為同一種型式。至於是彩色、 或黑白’僅由製程後段之色彩濾光片（color filter)之有 無來決定。 。 參照第1圖’其顯示Kodak公司製作之金氧半影像感測 器所使用之感光二極體PD之概要架構剖面圖。圖中，在一 具有隔離結構2之P型矽基底1中，形成一深N型摻雜區3， 而N型摻雜區3之上再形成一淺!^+摻雜區4。將複數個上述 感光二極體PD ’設置成為二維陣列之形態，再配置上色彩 慮光片FT，即成為彩色CMOS影像感測器。所配置之色彩濾 光片FT ’假設係採用Bayer之格式，則色彩濾光片FT上顏 色區域分佈，如第2圖R、G、B陣列標示之情形。圖中， R、G、B區域搭配各別之感光二極體，分別表示紅光、綠 光、藍光單元胞；並用以分辨不同波段之光線，而決定讓 光線穿越，促使感光二極體感光而產生光電流。 K〇dak公司製作之金氧半影像感測器所使用之感光二 極體’均係使用相同之型式之接面（junction)架構，如第As for the photodiode, the PN junction surface of silicon is mainly used to convert the intensity of incident light into photocurrent. Basically, a plurality of photodiodes are arranged as a photodiode array, which can be used as an image sensor, such as a CMOS imager. As far as the traditional metal-oxygen half-image sensor is concerned, whether it is color or black and white, the photodiodes used are of the same type. Whether it is color or black and white ’is determined only by the presence or absence of a color filter at the later stage of the process. . Referring to FIG. 1 ', a schematic cross-sectional view of a photodiode PD used in a metal-oxide semiconductor image sensor manufactured by Kodak Corporation is shown. In the figure, in a P-type silicon substrate 1 having an isolation structure 2, a deep N-type doped region 3 is formed, and a shallow! Doped region 4 is further formed on the N-type doped region 3. A plurality of the above-mentioned photodiodes PD 'are arranged in the form of a two-dimensional array, and then a color light-reflecting sheet FT is arranged to become a color CMOS image sensor. The configured color filter FT ′ is assumed to use the Bayer format, and the color area distribution on the color filter FT is as shown in the R, G, and B arrays in Figure 2. In the figure, the R, G, and B regions are equipped with different photodiodes, which respectively represent red, green, and blue light unit cells. They are used to distinguish light in different wavelength bands, and it is decided to let the light pass through to promote the photodiode to be sensitive. Instead, a photocurrent is generated. The photodiodes used by the metal oxide semiconductor image sensor produced by K〇dak Company all use the same type of junction structure.

4 185 4 24 185 4 2

圈所示為了達到較好之頻譜響應（f r equency response)和光感應度（sensitivity)，所以感光二極體ρρ 必須在可見光的各種波段均有良好之響應才行。 么〃例t在偏藍光部分，矽的感應吸收係數較大；而在偏 紅光部分’碎的感應吸收係數較小。因此，藍光在接觸矽 ，面不久後便幾乎完全被吸收而得到感應之光電流。但 疋’紅光在接觸矽表面後’需經過較長的距離，方能被吸 收以彳于感應之光電流。所以，感光二極體之結構即需設計 成如第1圖所示之接面結構；亦即’在一個感光二極體 中’需具備有極淺之PN接面（即第1圖中之N_p+接面，稱為 PN1) ’以便感應吸收藍光；另需具有空乏區大的之特性 即N-Psub間之接面間（稱為pN2)之空乏區要大，以便感應 吸收紅光。 為了達到上述目的，所以在以CMOS製程製作感光二極 體時’須使用多次離子植入（implant)，以進行調整而得 到所需之PN接面結構。但是，在同—感光二極體中進行多 次植入’將會造成過多的缺陷（defect)而形成白點（white Pixel )’如此將會影響最感測影像時之品質。另外，依第 1圖之架構之二極體’係需要有兩個接面結構PN1和pN2。 當接面（PN1)感光收集藍光所產生之電荷qpni時，接面 (PN 2 )必然收集到較少之電荷Qm。同理，當接面（pN2)感 光收集紅光所產生之電荷QPN2時’另一個接面（pN丨）必然收 集到較少之電何QPN1。所以’考量光感應度（Sensitivity) 如下式子所示As shown in the circle, in order to achieve a better frequency response and light sensitivity, the photodiode ρρ must have a good response in various wavelengths of visible light. In the example, the induction absorption coefficient of silicon is larger in the bluish light portion, and the induction absorption coefficient in the reddish light portion is smaller. Therefore, the blue light is almost completely absorbed shortly after contacting the silicon surface, and the induced photocurrent is obtained. However, it takes a long distance for 疋 ′ red light to contact the silicon surface before it can be absorbed to induce photocurrent. Therefore, the structure of the photodiode must be designed as shown in Figure 1; that is, 'in a photodiode' must have a very shallow PN junction (ie The N_p + junction is called PN1) 'in order to inductively absorb blue light; it also needs to have the characteristics of a large empty region, that is, the empty region between the junctions between N-Psub (called pN2) should be large in order to inductively absorb red light. In order to achieve the above purpose, when making a photodiode in a CMOS process, multiple ion implants must be used to adjust to obtain the desired PN junction structure. However, multiple implants in the same photodiode will cause too many defects to form white pixels. This will affect the quality of the most sensed image. In addition, the diode 'according to the structure of Fig. 1 needs to have two junction structures PN1 and pN2. When the interface (PN1) collects the charge qpni generated by the blue light sensitively, the interface (PN2) will necessarily collect less charge Qm. In the same way, when the junction (pN2) senses the charge QPN2 generated by the red light, the other junction (pN 丨) must collect less electricity and QPN1. So ‘considering light sensitivity (Sensitivity) is as follows

第5頁 4 18542 五、發明說明（3)Page 5 4 18542 V. Description of the invention (3)

Sensitivity: Qtotal/Ctotal = (QPN1+ Qpn2)/(CPNi+ CPN2) 就某一顏色之可見光而言，僅有一個PN接面會感光收集電 荷，另一PN接面僅僅相當於提供電容之作用而已，所以光 感應度會降低。 有鑑於此，本發明之目的’為提出一種具有多樣感光 二極體之彩色金氧半影像感測器。針對不同色彩單元胞， 製作不同之感光二極體’使得各個色彩單元胞中之感光二 極體，依其所感應可見光之不同，而分別具有不同之pN接 面深度；進而達到降低植入所造成之缺陷，以及提昇光感 應度。 為達到上述目的，本發明提出之有多樣感光二極體之 彩色金氧半影像感測器’至少包括：複數個感光二極體； 以及，遽光片，設置上述複數個感光二極體之上。 其中’每一上述感光二極體，係在一第—型基底 成一第二型摻雜區而構成；每一上述感光二極體内之/ 型摻雜區之深度’係依所要感測之可見光波長大小而=一 定’波長愈大則深度愈深、且濃度愈淺。另外，上廣” 片包括複數個顏色區分別配置給上述複數個感光二極=光 Ϊ得每—上述感光二極體得以分別感測特定波長之可I， 圖式之簡單說明： 為讓本發明之上述目的、特徵 '和優點能更 懂，下文特舉較佳實施例，並配合所附圖式，々 如下；其中，才目同之部分係以相同之符號表示故4細說明Sensitivity: Qtotal / Ctotal = (QPN1 + Qpn2) / (CPNi + CPN2) As far as visible light of a certain color is concerned, only one PN interface will collect light sensitively, and the other PN interface is only equivalent to providing a capacitor, so Light sensitivity will decrease. In view of this, an object of the present invention is to propose a color metal-oxide-semiconductor sensor with various photodiodes. For different color unit cells, different photodiodes are made, so that the photodiodes in each color unit cell have different pN junction depths according to the difference in the visible light they sense. Defects caused and increase light sensitivity. In order to achieve the above object, the color metal-oxide-semiconductor image sensor with various photodiodes provided by the present invention at least includes: a plurality of photodiodes; and a calender film, which is provided with the plurality of photodiodes. on. Wherein, each of the above-mentioned photosensitive diodes is constituted by a first-type substrate and a second-type doped region; the depth of each of the above-mentioned photosensitive diodes / type doped regions is determined as required. The wavelength of visible light is equal to a certain value. The larger the wavelength, the deeper the depth and the shallower the concentration. In addition, the "Shangguang" film includes a plurality of color regions that are respectively allocated to the plurality of photodiodes = light beams-each of the photodiodes can separately detect specific wavelengths. The simple description of the diagram is: The above-mentioned objects, features, and advantages of the invention can be more clearly understood. The preferred embodiments are described below in conjunction with the accompanying drawings, which are as follows; Among them, the same parts are represented by the same symbols.

五、發明說明⑷V. Description of Invention ⑷

，1圖顯示Kodak公司製作之金氧半影像感測器所使用 攻光二極體PD之概要架構剖面圖。 第2圖顯示依Bayer格式製作之濾光中，其r、G顏 £區分佈配置之情形。 y 光二極體DPB之概要架構 第3圖顯示吸收感應藍光之感 剖面圖。 第4圖顯示吸收感應紅光之感光二極體dpr之概要架構 面圖。 符號說明： 1〜P型矽基底；2 -隔離結構；3 '5、6〜N型摻雜區； 1 P、推雜區；PD~感光二極體；FT〜濾光片；DPB〜感應藍氺 之感光二極體；DPr〜感應紅光之感光二極體。 *、 實施例： 、本發明提出之具有多樣感光二極體之彩色金氧半影像 f須丨器’主要係針對不同色彩單元胞（〇〇1〇]： ce丨1)中之威 光二極體’製作單一之接面結構；且每個色彩單元胞中^ 感光二極體’依其所要感應吸收之可見光，而有不同之接 面深度。 依據本發明之彩色金氧半影像感測器，其基本架構至 少包括： 複數個感光二極體；以及，濾光片’設置上述複數個 感光二極體之上。 上述濾光片，例如使用第2圖所示Bayer格式之顏色區 分，包括複數個顏色區（每一顏色區’係由紅、綠、或Figure 1 shows a schematic cross-sectional view of the photodiode PD used by the metal-oxygen half-image sensor produced by Kodak. Figure 2 shows the distribution of the r and G color regions in the filter made in the Bayer format. y Photodiode DPB outline architecture Figure 3 shows a cross-sectional view of the sense of absorbing blue light. Figure 4 shows the schematic structure of a photodiode dpr that absorbs red light. Explanation of symbols: 1 ~ P type silicon substrate; 2-isolation structure; 3'5, 6 ~ N type doped regions; 1 P, doped region; PD ~ photodiode; FT ~ filter; DPB ~ sensing Blue Diode Photodiode; DPr ~ Red Diode Photosensitive Diode. *, Example: The color metal oxide half-image f-bearer with various photodiodes proposed by the present invention is mainly aimed at the light-emitting diodes in different color unit cells (〇〇１〇: ce 丨 1). The body 'makes a single interface structure; and each color cell has a ^ photodiode' which has different interface depths depending on the visible light that it will sense and absorb. The basic structure of the color metal-oxide semiconductor image sensor according to the present invention includes at least: a plurality of photodiodes; and a filter 'is disposed on the plurality of photodiodes. The above-mentioned filter, for example, uses the color regions of the Bayer format shown in FIG. 2 to include a plurality of color regions (each color region is made of red, green, or

4 185 4 2 五、發明說明（5) 藍）；其分別配置給上述複數個感光二極體，而分別形成 複數個單元胞，使得每一上述感光二極體得以分別感測特 定波長之可見光。 每一上述感光二極體，係在一 P型矽基底中形成一 N型 摻雜區而構成；每一上述感光二極體内之第二型摻雜區之 深度’係依所要感測之可見光波長大小而決定，波長愈大 則深度愈深。 第3圖顯示吸收感應藍光之感光二極體dpb之概要架構 剖面圖。依據本發明，以藍色單元胞（blue cel 1)而言， 藍光具有較小之波長’所以其感光二極體需使用深度較淺 且濃度較深之N+型摻雜區5，和P型矽基底構成pn接面結 構，如第3圖所示。 第4圖顯示吸收感應紅光之感光二極體j)pR之概要架構 剖面圖。依據本發明，以紅色單元胞（red ceil)而言，紅 光具有較長之波長，所以其感光二極體需使用深度較深且 濃度淡之N型摻雜區6，和p型矽基底構成㈣接面結構，如 第4圖所示，以便產生較大之空乏區。 同樣地’綠色單元胞也可以藉由調整接N型摻雜區之 深度，而得到適當之PN接面。 ，如上所述依據本發明’利用多樣不同接面深度結構之 感光二極體，來構成彩色金氧半影像感測器，有如下之 點： 由於在同一感光二極體中僅形成單一接面結構，所以 無需進行進行多次楂入之程序，因此可以避免產生過多的 五、發明說明（6) 缺陷’進而能夠確保感測影像之品質。 同一感光二極體形成單一 PN接面結構，故僅具有—個 接面電容存在，PN接面所感應之電荷，完全為單一接面電 容所接收，故光感應度不會下降。 雖然本發明已以較佳實 限疋本發明，任何熟悉本項 神和範圍内’當可做些許之 護範圍當視後附之申請專利 施例揭露如上，然其並非用以 技藝者，在不脫離本發明之精 更動和潤飾’因此本發明之保 範圍所界定者為準。4 185 4 2 V. Description of the invention (5) Blue); It is respectively allocated to the plurality of photodiodes, and forms a plurality of unit cells, so that each of the photodiodes can respectively detect visible light of a specific wavelength. . Each of the above-mentioned photosensitive diodes is formed by forming an N-type doped region in a P-type silicon substrate; the depth of the second-type doped region in each of the above-mentioned photosensitive diodes is determined as required. The wavelength of visible light depends on the size. The larger the wavelength, the deeper the depth. Fig. 3 shows a schematic structure of a photosensitive diode dpb that absorbs blue light. According to the present invention, in terms of the blue cell 1 (blue cel 1), blue light has a smaller wavelength, so its photodiode needs to use a deeper and deeper N + -type doped region 5, and a P-type. The silicon substrate forms the pn junction structure, as shown in Figure 3. Figure 4 shows the schematic structure of a photodiode j) pR that absorbs red light. According to the present invention, in terms of the red cell, red light has a longer wavelength, so its photodiode needs to use a deeper and lighter N-type doped region 6 and a p-type silicon substrate. Make up the joint structure, as shown in Figure 4, in order to create a large empty area. Similarly, the 'green cell' can also be adjusted to the depth of the N-type doped region to obtain a proper PN junction. As described above, according to the present invention, the use of various photodiodes with different junction depth structures to form a color metal-oxide semiconductor image sensor has the following points: Because only a single junction is formed in the same photodiode Structure, so there is no need to carry out multiple haw-in procedures, so you can avoid too many defects in the description of the invention (6) and further ensure the quality of the sensing image. The same photodiode forms a single PN junction structure, so there is only one junction capacitor. The charge induced by the PN junction is completely received by the single junction capacitor, so the light sensitivity will not decrease. Although the present invention has been limited to the present invention by a better practice, anyone familiar with this god and scope 'when there is a little scope of protection when the attached patent application examples are disclosed above, but it is not intended for a skilled person, Without deviating from the refinement and retouching of the present invention, therefore, what is defined by the scope of the present invention shall prevail.

Claims (1)

六 4 f 8 5 4 2 申請專利範圍6 4 f 8 5 4 2 patent application scope 器 1. 一種具有多樣感光二極體之彩色金氧半影像感剛 ，至少包括： 複數個感光二極體’每一上述感光二極體，係在一第 一型基底中开》成一第二型摻雜區而構成；每一上述感光二 極體内之第二型摻雜區之深度，係依所要感測之可見光& 長大小而決定，波長愈大則深度愈深、濃度愈淡；以及 濾光片’設置上述複數個感光二極體之上；其中，上 述;慮光片包括複數個顏色區分別配置給上述複數個感光二 極體’使得每一上述感光二極體得以分別感測特定波長之 可見光。 2 ·如申請專利範圍第1項所述之彩色金氧半影像感測 器’其中’上述第一型基底為P型矽基底，而上述第二蜇 摻雜區為N或N+型摻雜區。 口 .如申請專利範圍第1項所述之彩色金氧半影像感測 11 ’其中’上述複數個顏色區分別能夠讓紅、綠、藍三種 叮見光通過；而在上述複數感光二極體中，感測藍可見光 者之第二型摻雜區之深度最淺，感測紅可見光者之第二变 摻雜區之深度最深、濃度最淡。Device 1. A color metal oxide semi-image sensor with various photodiodes includes at least: a plurality of photodiodes, each of which is formed in a first type substrate and formed into a second The depth of the second type doped region in each of the above photodiodes is determined by the length of visible light & the larger the wavelength, the deeper the depth and the lighter the concentration. ; And a filter 'set on the plurality of photodiodes; wherein, the above; the light filter includes a plurality of color regions configured for the plurality of photodiodes', so that each of the above photodiodes can be separately Sensing visible light at a specific wavelength. 2 · The color metal-oxide-semiconductor image sensor according to item 1 of the scope of the patent application, wherein the above-mentioned first type substrate is a P-type silicon substrate, and the second erbium doped region is an N or N + type doped region . M. The color metal-oxygen half-image sensor 11 described in item 1 of the scope of the patent application 11 'wherein' the plurality of color regions can respectively allow red, green, and blue light to pass through; and the above-mentioned plurality of photodiodes Among them, the second type doped region that senses blue visible light has the shallowest depth, and the second variable doped region that senses red visible light has the deepest depth and the lightest concentration. 第10頁Page 10