TWI599024B - Image sensor and method for fabricating the same - Google Patents

Description

Image sensing element and manufacturing method thereof

The present invention relates to a method of fabricating an image sensing element, and more particularly to a method of fabricating a color filter using a patterned mask of a microlens.

With the continuous development and growth of electronic products such as digital cameras and scanners, the demand for image sensing components in the consumer market has continued to increase. In general, commonly used image sensing components include a charge coupled device (CCD sensor) and a CMOS image sensor (CIS). Among them, since the CMOS image sensing element has low operating voltage, low power consumption and high operational efficiency, random access can be performed as needed, and can be integrated into current semiconductor technology to be mass-produced, A wide range of applications.

The sensitization principle of the CMOS image sensing device is to distinguish the incident light into a combination of light of different wavelengths, and then receive them by a plurality of photosensitive elements on the semiconductor substrate, and convert them into digital signals of different strengths and weaknesses. For example, the incident light is divided into a combination of three colors of red, blue, and green light, and then received by a corresponding photodiode, and then converted into a digital signal. Therefore, a color filter array must be formed over each optical sensing element to distinguish the wavelength of the incident light.

However, it is conventional to form a color filter array by directly placing a plurality of color filters on a surface of a protective layer, and then sequentially covering the flat layer and forming a plurality of microlenses corresponding to the color filters. Since the color filter is fabricated on the protective layer, the design not only increases the path of light projection onto the photosensitive element in the semiconductor substrate, but also easily causes peeling of the color filter, which seriously affects the performance and goodness of the image sensing element. rate.

Therefore, the present invention is directed to a method of fabricating an image sensing element to solve the above-mentioned conventional problems.

A preferred embodiment of the invention discloses a method of fabricating an image sensing device, comprising the steps of: providing a substrate comprising a plurality of photosensitive diodes; forming at least one dielectric layer and a protective layer on the substrate a first pattern transfer process using a patterned mask to form a plurality of trenches corresponding to the respective photodiodes in the protective layer; forming a plurality of color filters in the recesses a planar layer is disposed on the color filters; and a second pattern transfer process is performed by the patterned mask to form a plurality of microlenses on the flat layer and corresponding to the color filters .

Another embodiment of the present invention discloses a method of fabricating an image sensing device, comprising the steps of: providing a substrate comprising a plurality of photodiodes; forming at least one dielectric layer and a protective layer on the substrate a first pattern transfer process is performed by using a patterned mask to form a plurality of grooves in the protective layer; a light shielding material is filled in the grooves to form a plurality of patterned light shielding layers; a plurality of color filters are disposed on the surface of the patterned light shielding layer and the protective layer; covering a flat layer on the color filters; and performing a second pattern transfer process by using the patterned mask to form a plurality of color filters A microlens is on the flat layer and corresponds to each of the color filters.

Another embodiment of the invention discloses an image sensing device, comprising: a substrate; a plurality of photosensitive diodes disposed in the substrate; at least one dielectric layer covering the substrate and the photosensitive diode; and a protective layer Provided on the surface of the dielectric layer; a plurality of patterned light shielding layers disposed in the protective layer; a plurality of color filters disposed on the surface of the protective layer and the surface of each of the patterned light shielding layers; a flat layer disposed on the color filter And a plurality of microlenses are disposed on the surface of the flat layer and correspond to the respective color filters, and each of the microlenses does not overlap the patterned light shielding layers.

Please refer to FIG. 1 to FIG. 2 . FIG. 1 to FIG. 2 are schematic diagrams showing an image sensing element according to a first embodiment of the present invention. As shown in the figure, a substrate 12, such as a germanium substrate, is first provided, and a sensor array region 14 is defined on the substrate 12. Then, a plurality of photodiodes 16 for collecting light, a plurality of complementary metal oxide semiconductor (CMOS) transistors (not shown), and a plurality of shallow trench isolations are formed in the substrate 12. STI) 18 surrounds each of the photosensitive diodes 16.

Then, an interlayer dielectric layer 20 is deposited on the substrate 12 and covers the CMOS transistor and the photodiode 16, and then the desired metal interconnection process is performed, that is, a plurality of dielectric layers are sequentially deposited. The electrical layer 22/24/26 is disposed on the interlayer dielectric layer 20, and a plurality of patterned metal layers 28/30/32 are formed in each of the dielectric layers 22/24/26 to form an image sensing element. Metal interconnects and increase the blocking effect of scattered light. In this embodiment, although three dielectric layers 22/24/26 are deposited on the interlayer dielectric layer 20, the number of the dielectric layers 22/24/26 and the patterned metal layer 28/30/32 can be regarded as the product requirements. Any adjustment is not limited to this.

A passivation layer 34 of a material such as tantalum nitride or hafnium oxide is deposited on the surface of the uppermost dielectric layer 26. Then, a pattern transfer process is performed, for example, a patterned mask 36 is first provided, and the pattern of the patterned mask 36 is aligned with an alignment mark (not shown) on the substrate 12 to be transferred to a negative pattern. Photoresist layer 38. Then, the negative patterned photoresist layer 38 is used as a mask to perform an etching process on the protective layer 34 and the dielectric layer 26, so as to form a plurality of corresponding layers in the protective layer 34 and the partial dielectric layer 26 respectively. The groove 16/42/44 of the pole body 16.

Next, as shown in FIG. 2, the patterned photoresist layer 38 is removed, and a plurality of color filters 46/48/50 are sequentially formed in the grooves 40/42/44 and cover the surface of the portion of the protective layer 34. For example, a blue filter material (not shown) may be first filled in the recess 40/42/44 and the protective layer 34, and then a blue filter is formed in the recess 40 by an exposure and development process. The light sheet 46 simultaneously removes the blue filter material within the recess 42/44. The exposure and development process is then repeated with the green and red filter materials to form a green filter 48 in the recess 42 and a red filter 50 in the recess 44. It should be noted that, in this embodiment, although the filters of three colors, such as blue, green, and red, are taken as an example, the color and combination of the color filters are not limited thereto, and may be selected from cyan. A filter, a magenta filter, a yellow filter, or the like, or a color combination of three or more color filters.

Then, a flat layer 52 is formed and covers the surfaces of the blue filter 46, the green filter 48, and the red filter 50, and then a plurality of microlenses 54/ are formed corresponding to the respective filters above the flat layer 52. 56/58. The microlens can be formed by first forming a polymer layer (not shown) composed of an acrylate material on the surface of the flat layer 52, and then using the same patterned light that previously formed the grooves 40/42/44. The cover 36 and the same alignment mark perform an exposure and development process on the polymer layer, and are combined with a reflow process for the relative blue filter 46, the green filter 48, and the red filter 50. A plurality of microlenses 54/56/58 are formed on the flat layer 52.

It should be noted that since the present invention uses the same patterned mask and the same alignment mark when etching the grooves 40/42/44 for forming the color filter and subsequently forming the microlenses 54/56/58, Thus, each microlens 54/56/58 is automatically aligned with each of the filters 46/48/50 when the fabrication of the microlenses 54/56/58 is completed. In addition, in this embodiment, a plurality of grooves are formed in the protective layer and a portion of the dielectric layer, and then the filters are filled in the grooves. In addition to shortening the path of the light reaching the photosensitive diode, the solution can be simultaneously solved. The problem of peeling caused by the color filter being formed on the surface of the protective layer is conventionally known.

It should be noted that the embodiment disclosed in FIG. 2 is directed to the structure of each photosensitive element disposed in the central region of the sensor array region 14, but is not limited thereto, and the above process can be combined with the movement of the microlens. Program shift is applied to the edge region of the sensor array area. As shown in FIG. 3, the present invention can apply the above-described process of forming a recess in the protective layer and filling the color filter to the central region 110 and the edge region 112 of the on-die sensor array region 14. In most cases, due to the shifting of the light, the microlenses of the edge region 112 are usually first subjected to a certain degree of shift after being judged by the program. As described in the previous embodiment, the two steps of forming the color filter of the color filter in the etching process and subsequently forming the microlens use the same patterned mask and the same alignment mark, so that the microlens 54/56 /58 When the program is transferred, the color filter 46/48/50 set below is aligned to achieve the effect of automatic alignment.

Please refer to FIG. 4 to FIG. 5 . FIG. 4 to FIG. 5 are schematic diagrams showing an image sensing element according to a second embodiment of the present invention. As shown in the figure, a substrate 62, such as a germanium substrate, is first provided, and a sensor array region 64 is defined on the substrate 62. Then, a plurality of photodiodes 66 for collecting light, a plurality of complementary metal oxide semiconductor (CMOS) transistors (not shown), and a plurality of shallow trench isolations 68 are formed in the substrate 62 to surround the photodiode 66. around.

An interlevel dielectric layer 70 is then deposited on the substrate 62 and covers the CMOS transistor and the photodiode 66, and then the desired metal interconnect process is performed, that is, a plurality of dielectrics are sequentially deposited. Layers 72/74 are formed on the interlayer dielectric layer 70, and a plurality of patterned metal layers 78/80 are formed in each of the dielectric layers 72/74 to form a metal interconnection of the image sensing element and increase scattering. The blocking effect of light. In this embodiment, although two dielectric layers 72/74 are deposited on the interlayer dielectric layer 70, the number of the dielectric layers 72/74 and the patterned metal layer 78/80 may be increased or decreased according to the demand of the product, and Limited to this.

A passivation layer 84 of a material such as tantalum nitride or hafnium oxide is deposited on the surface of the uppermost dielectric layer 74. Then, a pattern transfer process is performed, for example, a patterned mask 86 is first provided, and the pattern of the patterned mask 86 is aligned with an alignment mark (not shown) on the substrate 62 to be transferred to a positive pattern. Photoresist layer 88. Then, the positive-type patterned photoresist layer 88 is used as a mask to perform an etching process on the protective layer 84 and the dielectric layer 74 to form a plurality of non-shading photodiodes in the protective layer 84 and the portion of the dielectric layer 74. The grooves 90/92 of the body 66, for example, respectively correspond to shallow trench isolations 68 that surround the periphery of each of the photodiodes 66.

Next, as shown in FIG. 5, the patterned photoresist layer 88 is removed, and a plurality of patterned light-shielding layers 94 made of a light-shielding material are formed in the grooves 90/92. In the present embodiment, the patterned light shielding layer 94 is preferably composed of a black photoresist material. However, it is not limited thereto, and the patterned light shielding layer 94 may be composed of a metal such as a metal material such as tungsten metal. If the patterned light-shielding layer 94 is made of a photoresist material, a portion of the photoresist material disposed on the surface of the protective layer 84 can be removed by a plasma process after filling the recess 90/92; if the patterned light-shielding layer 94 is The metal material is formed by a chemical mechanical polishing (CMP) process after filling the grooves 90/92 to perform a planarization step on the metal material to fill the grooves 90/92. The inner light shielding material is flush with the surface of the protective layer 84.

A color filter array process is then performed using the same patterned mask 86 and the same alignment marks that previously formed the recesses 90/92 to form a plurality of blues on the surface of the planar patterned light-shielding layer 94 and the protective layer 84. A color filter array composed of a color filter 96, a green filter 98, and a red filter 100. As shown in the above, although the color filter of three colors, such as blue, green, and red, is taken as an example, the color and arrangement of the color filter array are not limited thereto, and may be selected from cyan filter. Other color filters such as a light sheet, a magenta filter, and a yellow filter, or an array of color filters constituting three or more colors, all of which are within the scope of the present invention .

A flat layer 102 is then formed and covers the surface of each filter 96/98/100, and then a plurality of microlenses 104/106/108 are formed above the flat layer 102 corresponding to each of the filters 96/98/100. The microlenses 104/106/108 may be formed by first forming a polymer layer (not shown) composed of an acrylate material on the surface of the flat layer 102, and then utilizing the same one previously formed into the grooves 90/92. The patterned mask 86 and the same alignment mark perform an exposure and development process on the polymer layer, and are subjected to a thermal reflow process to form on the flat layer 102 of each of the filters 96/98/100. A plurality of microlenses 104/106/108.

Compared with the first embodiment described above, the present embodiment mainly uses the same patterned mask to etch the grooves 90/92 and the subsequent microlenses 104/106/108 forming the patterned light shielding layer 94, and The 90/92 patterned photoresist layer 88 is a positive photoresist, so that the formed microlenses 104/106/108 edges are preferably offset from the edges of the patterned light shielding layer 94 and do not overlap each other.

Therefore, according to the process described in FIG. 5, the present invention further discloses a structure of an image sensing element. As shown in the figure, the image sensing element mainly comprises a substrate 62; a plurality of photosensitive diodes 66 are disposed in the substrate 62; an interlayer dielectric layer 70 is disposed on the surface of the substrate 62 and the photosensitive diode 66; A plurality of dielectric layers 72/74 are overlying the interlayer dielectric layer 70; a plurality of patterned metal layers 78/80 are disposed in the dielectric layer 72/74; a protective layer 84 is disposed on the surface of the dielectric layer 72/74; A plurality of patterned light shielding layers 94 are disposed in the protective layer 84 and a portion of the dielectric layer 74; a plurality of color filters 96/98/100 are disposed on the surface of the protective layer 84; and a flat layer 102 is disposed on the color filter 96/ 98/100; and a plurality of microlenses 104/106/108 are disposed on the surface of the flat layer 102 and correspond to the respective color filters 96/98/100.

In the present embodiment, the edges of the respective microlenses 104/106/108 preferably do not overlap the patterned light shielding layers 94. In addition, the color filter 96/98/100 may be selected from the group consisting of a red filter, a green filter, a blue filter, a cyan filter, a magenta filter, and a yellow filter, and the like, and The patterned light shielding layer 94 may be selected from a black photoresist material or a metal material such as tungsten.

In addition, it should be noted that the embodiment disclosed in FIG. 5 is an improved design for the central region of the sensor array region 64, but is not limited thereto, and the present invention may be further in accordance with the embodiment disclosed in FIG. The process of Figures 4-5 is applied to the edge regions of the sensor array area 64 on the die. As shown in FIG. 6, the present invention can apply the process of forming the patterned light shielding layer 94 and the color filter array in the protective layer 84 to the central region 114 and the edge region 116 of the sensor array region 64 to produce Another type of image sensing element structure. As shown in the figure, even though the microlenses 104/106/108 of the edge region 116 of the sensor array region 64 are slightly shifted by the program to correspond to the position of the photodiode 66, the patterned light shielding layer 94 is formed. The same patterned reticle and the same alignment mark are used in both steps of the microlens 104/106/108, so that the microlens 104/106/108 edge is still preferably not overlapped with any patterned light shielding layer 94. .

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

12. . . Base

14. . . Sensor array area

16. . . Photosensitive diode

18. . . Shallow trench isolation

20. . . Interlayer dielectric layer

twenty two. . . Dielectric layer

twenty four. . . Dielectric layer

26. . . Dielectric layer

28. . . Patterned metal layer

30. . . Patterned metal layer

32. . . Patterned metal layer

34. . . The protective layer

36. . . Patterned mask

38. . . Patterned photoresist layer

40. . . Groove

42. . . Groove

44. . . Groove

46. . . Filter

48. . . Filter

50. . . Filter

52. . . Flat layer

54. . . Microlens

56. . . Microlens

58. . . Microlens

62. . . Base

64. . . Sensor array area

66. . . Photosensitive diode

68. . . Shallow trench isolation

70. . . Interlayer dielectric layer

72. . . Dielectric layer

74. . . Dielectric layer

78. . . Patterned metal layer

80. . . Patterned metal layer

84. . . The protective layer

86. . . Patterned mask

88. . . Patterned photoresist layer

90. . . Groove

92. . . Groove

94. . . Patterned shading layer

96. . . Filter

98. . . Filter

100. . . Filter

102. . . Flat layer

104. . . Microlens

106. . . Microlens

108. . . Microlens

110. . . Central area

112. . . Edge area

114. . . Central area

116. . . Edge area

1 to 2 are schematic views showing an image sensing element produced in accordance with a first embodiment of the present invention.

Figure 3 is a schematic view showing the structure of the first embodiment of the present invention applied to the edge region of the sensor array region.

4 to 5 are schematic views showing the fabrication of an image sensing element according to a second embodiment of the present invention.

Figure 6 is a schematic view showing the structure of the second embodiment of the present invention applied to the edge region of the sensor array region.

12. . . Base

14. . . Sensor array area

16. . . Photosensitive diode

18. . . Shallow trench isolation

20. . . Interlayer dielectric layer

twenty two. . . Dielectric layer

twenty four. . . Dielectric layer

26. . . Dielectric layer

28. . . Patterned metal layer

30. . . Patterned metal layer

32. . . Patterned metal layer

34. . . The protective layer

46. . . Filter

48. . . Filter

50. . . Filter

52. . . Flat layer

54. . . Microlens

56. . . Microlens

58. . . Microlens

Claims (17)

A method of fabricating an image sensing device, comprising: providing a substrate comprising a plurality of photosensitive diodes; forming at least one dielectric layer and a protective layer on the surface of the substrate; and performing a pattern using a patterned mask a pattern transfer process to form a plurality of trenches corresponding to the respective photodiodes in the protective layer and a portion of the dielectric layer; forming a plurality of color filters in the grooves; covering one a flat layer on the color filters; and a second pattern transfer process using the patterned mask to form a plurality of microlenses on the flat layer and corresponding to the color filters. The method of claim 1, wherein the color filter is selected from the group consisting of a red filter, a green filter, a blue filter, a cyan filter, and a magenta (magenta). ) Filters, and yellow filters. The method of claim 1, wherein the first pattern transfer process comprises: forming a patterned photoresist layer on the surface of the protective layer; transferring the patterned mask pattern to the patterned photoresist layer And using the patterned photoresist layer as a mask to perform an etching process on the protective layer to form the recesses. The method of claim 3, wherein the patterned photoresist layer comprises a negative photoresist. The method of claim 1, wherein the second pattern transfer process further comprises: forming a polymer layer on the flat layer; and performing an exposure and development process on the polymer layer by using the patterned mask; And performing a thermal reflow process to form the microlenses. The method of claim 1, wherein the performing the first pattern transfer process further comprises forming the color filters in the grooves and covering a portion of the surface of the protective layer. A method of fabricating an image sensing device, comprising: providing a substrate comprising a plurality of photosensitive diodes; forming at least one dielectric layer and a protective layer on the surface of the substrate; and performing a pattern using a patterned mask a pattern transfer process to form a plurality of recesses in the protective layer and a portion of the dielectric layer; filling a light-shielding material in the recesses to form a plurality of patterned light-shielding layers; forming a plurality of color filters Filming the patterned light shielding layer and the protective layer a surface; covering a flat layer on the color filters; and performing a second pattern transfer process using the patterned mask to form a plurality of microlenses on the flat layer and corresponding to the color filters. The method of claim 7, wherein the color filter is selected from the group consisting of a red filter, a green filter, a blue filter, a cyan filter, a magenta filter, and Yellow filter. The method of claim 7, wherein the first pattern transfer process comprises: forming a patterned photoresist layer on the surface of the protective layer; and transferring the patterned mask pattern to the patterned photoresist layer And using the patterned photoresist layer as a mask to perform an etching process on the protective layer to form the recesses. The method of claim 9, wherein the patterned photoresist layer comprises a positive photoresist. The method of claim 7, wherein the second pattern transfer process further comprises: forming a polymer layer on the flat layer; and performing an exposure and development process on the polymer layer by using the patterned mask; And performing a thermal reflow process to form the microlenses. The method of claim 7, wherein the color filter is further disposed to remove the light shielding material disposed on the surface of the protective layer by plasma to form the patterned light shielding layer, and the method The patterned light shielding layer is flush with the surface of the protective layer. An image sensing component comprises: a substrate; a plurality of photosensitive diodes disposed in the substrate; at least one dielectric layer covering the substrate and the photosensitive diode; a protective layer disposed on the substrate a plurality of patterned light-shielding layers are disposed in the protective layer and a portion of the dielectric layer; a plurality of color filters are disposed on the surface of the protective layer and the surface of each of the patterned light-shielding layers; a flat layer The plurality of microlenses are disposed on the surface of the flat layer and correspond to the color filters, and each of the microlenses does not overlap each of the patterned light shielding layers. The image sensing device of claim 13, wherein the image sensing device further comprises a plurality of patterned metal layers disposed in the dielectric layer. The image sensing device of claim 13, wherein the color filter is selected from the group consisting of a red filter, a green filter, a blue filter, a cyan filter, and a magenta filter. Sheet, and yellow filter. The image sensing element of claim 13, wherein the patterned light shielding layer comprises a black photoresist material. The image sensing element of claim 13, wherein the patterned light shielding layer comprises tungsten metal.