TWI741934B - Optical apparatus, optical system, time-of-flight system and three-dimensional imaging system - Google Patents

Abstract

An apparatus including a semiconductor substrate; an absorption layer coupled to the semiconductor substrate, the absorption layer including a photodiode region configured to absorb photons and to generate photo-carriers from the absorbed photons; one or more first switches controlled by a first control signal, the one or more first switches configured to collect at least a portion of the photo-carriers based on the first control signal; and one or more second switches controlled by a second control signal, the one or more second switches configured to collect at least a portion of the photo-carriers based on the second control signal, where the second control signal is different from the first control signal.

Description

Optical device, optical system, time difference ranging system and stereo imaging system

The present invention relates to optical devices, and particularly to high-speed light sensing devices.

The optical sensor is mainly used to convert the optical signal transmitted in a free space (or in an optical medium) and coupled to it into an electrical signal for subsequent processing.

According to the present invention, the light reflected by a three-dimensional object can be sensed by a plurality of photodiodes in an imaging system. The photodiode converts the sensed light into complex charges. Each photodiode may include two groups of switches, and the two groups of switches are used to collect the aforementioned charges. The two groups of switches used to collect the charge can be switched in time sequence, so that the imaging system can determine the phase information based on the sensed light.

The imaging system can use the image information to analyze the characteristics of the three-dimensional object, including depth information and a material composition. The imaging system can also use phase information for eye tracking, gesture recognition, 3D object scanning/image capture, and/or augmented/virtual reality applications.

The present invention provides an optical device, which includes a semiconductor substrate; a germanium silicon layer is coupled to the semiconductor substrate, and the germanium silicon layer includes a photodiode region for absorbing multiple photons And generate a plurality of photocarriers; one or more first switches, one or more first switches according to a first control signal, and the one or more switches collect at least a part of the photocarriers according to the first control signal And one or more second switches, a second control signal controls the one or more second switches, the one or more second switches collect at least a part of the photocarriers according to the second control signal . The one or more first switches include a first p-type doped region, the first p-type doped region is located in the germanium silicon layer, wherein the first control signal controls the first p-type doped region; and a second An n-type doped region, the first n-type doped region is located in the germanium silicon layer, and the first n-type doped region is coupled to a first readout integrated circuit. The one or more second switches include a second p-type doped region, the second p-type doped region is located in the germanium silicon layer, wherein the second control signal controls the second p-type doped region; and a first Two n-type doped regions, the second n-type doped region is located in the germanium silicon layer, and the second n-type doped region is coupled to the second readout integrated circuit.

One or more of the following features can be optionally included in an embodiment of the present invention. The germanium silicon layer includes a third n-type doped region and a fourth n-type doped region, wherein at least a part of the first p-type doped region can be formed in the third n-type doped region, and the second p-type doped region At least a part of the impurity region may be formed in the fourth n-type doped region. At least a part of the first p-type doped region and at least a part of the second p-type doped region may be formed in the third n-type doped region. The semiconductor substrate may include a third p-type doped region and one or more n-type doped regions, the germanium-silicon layer may be disposed above the third p-type doped region, and the third p-type doped region may be short-circuited to The one or more n-type doped regions.

The first control signal can be a fixed bias, the second control signal can be an adjustable bias, and the adjustable bias of the second control signal is greater than the fixed bias of the first control signal Pressure. The photons absorbed by the germanium silicon layer can be reflected from a surface of a three-dimensional object, and part of the photons collected by the one or more first switches and part of the photons collected by the one or more second switches can be used A time difference ranging system analyzes the depth information of a three-dimensional object or a material composition.

According to the present invention, another optical device is provided, which includes: a semiconductor substrate; an absorption layer coupled to the semiconductor substrate, the absorption layer includes a photodiode region, the photodiode region is used to absorb multiple photons and generate multiple light carriers One or more first switches, a first control signal controls the one or more first switches, and the one or more first switches collect at least a part of the photocarriers according to the first control signal And one or more second switches, a second control signal controls the one or more second switches, and the one or more second switches collect at least a part of the photocarriers according to the second control signal . The one or more first switches include: a first p-type doped region located in the semiconductor substrate, and a first control signal controls the first p-type doped region; and a first n-type doped region located in In the semiconductor substrate, the first n-type doped region is coupled to a first readout integrated circuit. The one or more second switches include: a second p-type doped region located in the semiconductor substrate, the second control signal controls the second p-type doped region; and a second n-type doped region located in the semiconductor substrate In the substrate, the second n-type doped region is coupled to a second readout integrated circuit.

One or more of the following features can be optionally included in an embodiment of the present invention. The semiconductor substrate may include a third n-type doped region and a fourth n-type doped region, at least a part of the first p-type doped region may be formed in the third n-type doped region, and a second p-type doped region At least a part of the impurity region may be formed in the fourth n-type doped region. The semiconductor substrate may include a The third n-type doped region, at least a part of the first p-type doped region and at least a part of the second p-type doped region may be formed in the third n-type doped region. The semiconductor substrate may include one or more p-type well regions.

The first control signal may be a fixed bias voltage, the second control signal may be an adjustable bias voltage, and the adjustable bias voltage of the second control signal is greater than the fixed bias voltage of the first control signal. The photons absorbed by the germanium silicon layer can be reflected from a surface of a three-dimensional object, and part of the photons collected by the one or more first switches and part of the photons collected by the one or more second switches can be used A time difference ranging system analyzes the depth information of a three-dimensional object or a material composition.

According to the present invention, there is further provided an optical device, including: a semiconductor substrate; an absorption layer coupled to the semiconductor substrate, the absorption layer includes a photodiode region, the photodiode region is used to absorb multiple photons and generate multiple photocarriers One or more first switches, a first control signal controls the one or more first switches, and the one or more first switches collect at least a part of the photocarriers according to the first control signal; And one or more second switches, a second control signal controls the one or more second switches, and the one or more second switches collect at least a part of the photocarriers according to the second control signal. The one or more first switches include: a plurality of first p-type doped regions located in the semiconductor substrate, and a first control signal controls the first p-type doped regions; and a first n-type doped region, Located in the semiconductor substrate, the first n-type doped region is coupled to a first readout integrated circuit. The one or more second switches include: a plurality of second p-type doped regions located in the semiconductor substrate, and the second control signal controls the second p-type doped regions; And a second n-type doped region located in the semiconductor substrate, wherein the second n-type doped region is coupled to a second readout integrated circuit.

One or more of the following features can be optionally included in an embodiment of the present invention. The semiconductor substrate may include a third n-type doped region, at least a part of the first p-type doped region may be formed in the third n-type doped region, and at least a part of the second p-type doped region may be formed in the third In the n-type doped region. The first p-type doped region and the second p-type doped region can be arranged in a cross along a first plane of the semiconductor substrate, and the first n-type doped region and the second n-type doped region can be arranged along a first plane of the semiconductor substrate. A second plane is arranged in a cross, and the second plane is different from the first plane. Any p-type doped region in the plurality of first p-type doped regions may be arranged above one n-type doped region of the plurality of first n-type doped regions, and the second p-type doped region Any p-type doped region may be arranged above one of the plurality of second n-type doped regions. The semiconductor substrate may include one or more p-type well regions.

The first control signal may be a fixed bias voltage, the second control signal may be an adjustable bias voltage, and the adjustable bias voltage of the second control signal is greater than the fixed bias voltage of the first control signal. The photons absorbed by the germanium silicon layer can be reflected from a surface of a three-dimensional object, and part of the photons collected by the one or more first switches and part of the photons collected by the one or more second switches can be used A time difference ranging system analyzes the depth information of a three-dimensional object or a material composition.

The present invention further provides a time difference ranging system, including: a light source; and an image sensor, including a plurality of pixels, the pixels are fabricated on a semiconductor substrate. Each pixel includes: a germanium silicon layer coupled to the semiconductor substrate, the germanium silicon layer includes a photodiode region, the photodiode region is used to absorb multiple photons and generate multiple photocarriers; one or more A first switch, a first control signal controls the one or more first switches, the one or more first switches collect a part of the photocarriers according to the first control signal; and one or more The second switch, a second control signal controls the one or more second switches, and the one or more second switches collect a part of the photocarriers according to the second control signal, wherein the second control signals are different In the first control signal.

An embodiment of the present invention may optionally include one or more of the following features: the light source is used to emit a plurality of light pulses, one of the light pulses has a duty cycle of less than 50%, and each light pulse has the same energy.

The present invention also provides an optical device, including: a semiconductor substrate; a germanium silicon layer coupled to the semiconductor substrate, the germanium silicon layer includes a photodiode region, the photodiode region is used to absorb multiple photons and generate multiple light carriers One or more first switches, a first control signal controls the one or more first switches, and the one or more first switches collect a part of the photocarriers according to the first control signal; And one or more second switches, a second control signal controls the one or more second switches, the one or more second switches collect a part of the photocarriers according to the second control signal, the first The second control signal is different from the first signal. The one or more first switches include: a first p-type doped region located in the germanium silicon layer, and a first control signal controls the first p-type doped region; and a first n-type doped region, Located in the semiconductor substrate, the first n-type doped region is coupled to a first readout integrated circuit. The one or more second switches include: a second p-type doped region located in the germanium silicon layer, the second control signal controls the second p-type doped region; and a second n-type doped region, Located in the semiconductor substrate, the second n-type doped region is coupled to a second readout integrated circuit.

One or more of the following features can be optionally included in an embodiment of the present invention. The germanium-silicon layer may include a third n-type doped region and a fourth n-type doped region, at least a part of the first p-type doped region may be formed in the third n-type doped region, and the second p-type doped region At least a part of the impurity region may be formed in the fourth n-type doped region. The silicon germanium layer may include a third n-type doped region, and at least a part of the first p-type doped region and at least a part of the second p-type doped region may be formed in the third n-type doped region. The semiconductor substrate may include one or more p-type well regions.

The first control signal may be a fixed bias voltage, the second control signal may be an adjustable bias voltage, and the adjustable bias voltage of the second control signal is greater than the fixed bias voltage of the first control signal. The photons absorbed by the germanium silicon layer can be reflected from a surface of a three-dimensional object, and part of the photons collected by the one or more first switches and part of the photons collected by the one or more second switches can be used A time difference ranging system analyzes the depth information of a three-dimensional object or a material composition.

One or more of the following features can be optionally included in an embodiment of the present invention. Germanium is a material with a high absorption coefficient for infrared light, which can reduce the problem of slow recombination of photo-generated carriers in the depths of the substrate caused by materials with poor absorption coefficient for infrared light (such as silicon). For a photodiode with a p-type doped region and an n-type doped region and are fabricated at different depths, the photocarrier transmission distance is limited by the depth of the absorbing material rather than the width; therefore, if you use With an absorbing material with a short absorption length, the distance between the p-type doped region and the n-type doped region can be shortened. In this way, a small bias voltage can also create a strong electric field, thereby increasing the operating speed. In a photodiode, two groups of switches can be inserted or arranged vertically in a staggered arrangement, such a time difference ranging system can collect different light Phase photocarriers. The increase in operating speed allows the use of high modulation frequencies in the time difference ranging system, which in turn can increase the depth of resolution. In the time difference ranging system, the reduction of the duty cycle of the optical pulse can increase the peak intensity of the optical pulse. As a result, the signal-to-noise ratio of the time difference ranging system can be improved while maintaining the same power loss adjustment components. This allows the light pulse to reduce the duty cycle of the light pulse without the pulse shape being distorted.

The details of one or more implementation manners of the present invention will be described in conjunction with the following drawings. From the detailed description, drawings, and patent scope of the present invention, other possible features and advantages of the present invention can be more clearly understood.

100, 160, 170, 180, 200, 250, 260, 270, 300, 360, 370, 380, 400, 450, 460, 470, 480: double switch photodiode

102, 202, 302, 402: substrate

106, 206, 306, 406: absorption layer

108, 208, 308a, 308b, 408: the first switch

110, 210, 310a, 310b, 410: second switch

112, 212, 312, 412: optical signal

116, 214, 216, 314, 316, 416: external control

122, 222, 322, 422: the first control signal

124, 224, 324, 424: first readout circuit

132, 232, 332, 432: second control signal

134, 234, 334, 434: second readout circuit

126, 136, 226, 236, 326a, 326b, 336a, 336b, 426, 436: n-type doped regions

128, 138, 209, 228, 238, 309, 328a, 328b, 338a, 338b, 428, 438: p-type doped regions

142, 144, 152, 154, 156, 244, 252, 254, 344, 452, 454, 456, 458: n-type well area

246, 248, 346, 348, 446, 448: p-type well area

362: first plane

364: second plane

502: Transmission Unit

504: receiving unit

506: Processing Unit

510: Target Object

512: light pulse

514: reflected light pulse

Figure 1A, Figure 1B, Figure 1C, and Figure 1D respectively show a schematic diagram of a dual-switch photodiode; Figure 2A, Figure 2B, Figure 2C, and Figure 2D respectively show a schematic diagram of a dual-switch photodiode; Figure 3A , Figures 3B, 3C, and 3D respectively show schematic diagrams of a dual-switch photodiode; Figures 4A, 4B, 4C, 4D, and 4E show schematic diagrams of a dual-switch photodiode, respectively; 5A shows a block diagram of an imaging system; FIGS. 5B and 5C show schematic diagrams of the technique of using an imaging system to determine the characteristics of an object; and FIG. 6 illustrates a flowchart of using an imaging system to determine the characteristics of an object.

One or more embodiments of the present disclosure will be illustrated in the drawings of the drawings through examples without limiting meaning, in which the same component symbols represent the same components. These drawings are not necessarily drawn to scale.

The photodiode can be used to sense optical signals and convert the sensed optical signals into electrical signals for subsequent signal processing by other circuits. In time-of-flight (TOF) applications, the depth information of a three-dimensional object can be measured using a phase difference between a transmitted light pulse and a sensing light pulse. For example, a two-dimensional array of pixels can be used to reconstruct a three-dimensional image of a three-dimensional object; wherein each pixel can include one or more photodiodes for obtaining phase information of the three-dimensional object. In some embodiments, the time difference ranging application uses a light source with a near-infrared light band; for example, a light-emitting diode with a wavelength of 850 nm, 940 nm, or 1050 nm. Although some photodiodes use silicon as an absorbing material, silicon does not absorb light signals in the near-infrared band well. More specifically, photocarriers are generated from deep parts of the silicon substrate (for example, at a depth greater than 10μm). These photocarriers can slowly drift and/or diffuse to the photodiode junction, which makes the device's operation speed . Furthermore, in normal use, a small amplitude voltage is applied to control the operation of the photodiode to reduce power loss. For a large absorption region (for example, a diameter of 10 μm), a small amplitude voltage can establish a small lateral/longitudinal field across the large absorption region, which will affect the drift speed of photocarriers passing through the absorption region. The operating speed of the device can be further restricted. Aiming at the application of time difference ranging using near-infrared light, the present invention proposes a dual-switch photodiode design structure and/or a dual-switch photodiode using germanium silicon as an absorbing material. In this article, the term "photodiode" used can be used as a synonym for the term "optical sensor"; secondly, the term "germanium-silicon (germanium-silicon; molecular formula GeSi)" is used. In the germanium-silicon alloy referred to, the germanium content is 10% to 100%, which means that the silicon content is 0% to 90%. In this article, the germanium-silicon layer can use blanket epitaxy technology, select It can be achieved by selective epitaxy technology or other technologies. In addition, an absorber layer containing germanium-silicon material can be formed on a plane, a top surface of a platform, or a bottom surface of a trench, and at least partly surrounds an insulator (e.g., oxide, nitride), a semiconductor (e.g., germanium, Silicon), or a combination thereof. A strained super lattice structure or a multi-quantum well structure may include multiple layers, such as selective silicon germanium layers with different silicon and germanium contents.

FIG. 1 shows a schematic diagram of a dual-switch photodiode 100, which is used to convert an optical signal into an electrical signal. The double-switch photodiode 100 includes an absorption layer 106 formed on a substrate 102. The substrate 102 may be a substrate suitable for fabricating a semiconductor device thereon. For example, the substrate 102 may be a silicon substrate. The absorption layer 106 includes a first switch 108 and a second switch 110.

Generally, the absorption layer 106 receives an optical signal 112 and converts the optical signal 112 into a complex electrical signal. The absorption layer 106 can be selected to have a high absorption coefficient for the optical signal of the required wavelength. If the optical signal 112 is infrared light, the absorption layer 106 can be a germanium silicon platform; wherein the germanium silicon absorbs the photons in the optical signal 112 and generates electron-hole pairs. The germanium content and silicon content in the germanium silicon platform can be determined according to the process conditions and application fields. In some embodiments, the absorption layer 106 is designed to have a thickness t. For example, for an optical signal 112 with a wavelength of 850 nanometers (nm), the thickness of the germanium-silicon platform is about 1 micrometer (μm), so that it has a considerable quantum efficiency. In some embodiments, the surface of the absorption layer 106 can be designed to have a specific shape; for example, the shape of the germanium silicon platform can be circular, square, or rectangular according to the spatial distribution of the light signal 112 on the germanium silicon platform . In some embodiments, the absorbent layer 106 can be designed to have a lateral dimension to The light signal 112 is received. For example, the germanium silicon mesa can be circular, and its lateral dimension d can range from 1 μm to 50 μm.

A first switch 108 and a second switch 110 are fabricated in the absorption layer 106. The first switch 108 is coupled to a first control signal 122 and a first readout circuit 124; the second switch 110 is coupled to a second Control signal 132 and a second readout circuit 134. The first readout circuit 124 or the second readout circuit 134 decides to collect electrons or holes according to the control of the first control signal 122 and the second control signal 132.

In some embodiments, the first switch 108 and the second switch 110 are used to collect multiple electrons; under the aforementioned conditions, the first switch 108 includes a p-type doped region 128 and an n-type doped region 126. For example, the p-type doped region 128 may have a p+ doping, and its activated dopant concentration may be the highest impurity concentration achievable by the process; for example, when the absorber layer 106 is germanium and boron is doped therein At this time, the highest concentration of p+ doping can be 5x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the p-type doped region 128 may be lower than 5× ^{10 20} cm ⁻³ , thereby simplifying the manufacturing complexity while increasing the contact resistance. An n-type doped region 126 can have an n+ doping, and its activation impurity concentration can be the highest impurity concentration achievable by the process; for example, when the absorber layer 106 is germanium and doped with phosphorus, the highest n+ doping concentration can be 1x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the n-type doped region 126 can be lower than 1×10 ²⁰ cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The distance between the p-type doped region 128 and the n-type doped region 126 can be designed according to the process conditions; in general, the closer the distance between the p-type doped region 128 and the n-type doped region 126, the light carrier The switching efficiency of the child is higher. The second switch 110 includes a p-type doped region 138 and an n-type doped region 136, the p-type doped region 138 is similar to the p-type doped region 128, and the n-type doped region 136 is similar to the n-type doped region 126.

In some embodiments, the p-type doped region 128 is coupled to the first control signal 122; for example, the p-type doped region 128 can be coupled to a voltage source, wherein the first control signal 122 can be a voltage source Provide an AC voltage signal. In some embodiments, the n-type doped region 126 is coupled to the readout circuit 124. The readout circuit 124 may be a three-transistor structure composed of a reset gate, a source-follower and a selection gate. Or other circuits used to process charge. In some embodiments, the readout circuit 124 can be fabricated on the substrate 102. In some embodiments, the readout circuit 124 can be fabricated on another substrate and form a common package with the dual-switch photodiode 100 using chip/wafer bonding or stacking technology.

The p-type doped layer 138 is coupled to the second control signal 132. For example, the p-type doped region 138 may be coupled to a voltage source; wherein, the second control signal 132 may be an AC voltage signal, and an AC voltage signal whose phase is opposite to the first control signal 122. In some embodiments, the n-type doped region 136 can be coupled to the readout circuit 134. The readout circuit 134 may be similar to the readout circuit 124.

The first control signal 122 and the second control signal 132 are used to control the collection of complex electrons generated by the absorption of photons. For example, if the first control signal 122 is different from the second control signal 132, an electric field will be established between the p-type doped region 128 and the p-type doped region 138, and the free electrons will be drawn to the p-type according to the direction of the aforementioned electric field. The doped region 128 or the p-type doped region 138 drifts. In some embodiments, the first control signal 122 can be fixed at a voltage Value Vi, the second control signal 132 can alternate between the voltage value Vi±ΔV. The direction of the bias value determines the drift direction of electrons. Accordingly, when one of the switches (for example, the first switch) is turned on (that is, electrons drift to the p-type doped region 128), the other switch (for example, the second switch 110) is turned off (that is, the electrons are switched from the p-type doped region 128). The doped region 138 is blocked). In some embodiments, the first control signal 122 and the second control signal 132 may have different voltage values.

Generally speaking, the Fermi level difference between a p-type doped region and an n-type doped region creates an electric field between the two regions. In the first switch 108, an electric field is established between the p-type doped region 128 and the n-type doped region 126; similarly, in the second switch 110, an electric field is established between the p-type doped region 138 and the n-type doped region 126. Between n-type doped regions 136. When the first switch 108 is turned on and the second switch 110 is turned off, electrons are attracted by the p-type doped region 128, and the electric field between the p-type doped region 128 and the n-type doped region 126 further allows the electrons to be doped to the n-type Miscellaneous area 126 passes. The readout circuit 124 can then process the charges collected by the n-type doped region 126. On the other hand, when the second switch 110 is turned on and the first switch 108 is turned off, the p-type doped region 138 collects electrons; the electric field between the p-type doped region 138 and the n-type doped region 136 allows the electrons to The n-type doped region 138 is transferred. The readout circuit 134 can then process the electrons collected by the n-type doped region 136.

In some embodiments, a voltage can be applied between the p-type doped region and the n-type doped region of a switch to allow the switch to operate in a sudden avalanche mechanism to increase the sensitivity of the dual-switch photodiode 100. For example, when the distance between the p-type doped region 128 and the n-type doped region 126 is about 100 nanometers, a voltage lower than 7 volts can be applied to the p-type doped region 128 and the n-type doped region. Create sudden collapse gain between areas 126.

In some embodiments, the substrate 102 can be coupled to an external control 116. For example, the substrate 102 may be coupled to ground. In some embodiments, the substrate 102 may be floating or not coupled to any external control.

FIG. 1B shows a schematic diagram of a dual-switch photodiode 160 used to convert optical signals into electrical signals. The dual-switch photodiode 160 is similar to the dual-switch photodiode 100 shown in FIG. 1A, but the first switch 108 and the second switch 110 further include an n-type well region 152 and an n-type well region 154, respectively . In addition, the absorption layer 106 may be a p-type doped region. In some embodiments, the doping level of the n-type well regions 152 and 154 can be from 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 , and the doping level of the absorption layer 106 can be from 10 ¹⁴ cm ^-3 to 10 ¹⁶ cm ^-3. .

The arrangement of the p-type doped region 128, the n-type well region 152, the p-type doped absorber layer 106, the n-type well region 154, and the p-type doped region 138 forms a PNPNP junction structure. Generally speaking, the PNPNP junction structure can reduce a conduction current from the first control signal 122 to the second control signal 132, or selectively reduce the conduction current from the second control signal 132 to the first control signal 122. The arrangement of the n-type doped region 126, the p-type doped absorption layer 106, and the n-type doped region 136 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 124 to the second readout circuit 134, or selectively reduce the charge coupling from the second readout circuit 134 to the first readout circuit 124 .

In some embodiments, the p-type doped region 128 may be completely formed in the n-type well region 152. In some embodiments, the p-type doped region 128 may be partially formed in the n-type well region 152. For example, a part of the p-type doped region 128 can be implemented by implanting p-type impurities in the n-type well region 152, and another part of the p-type doped region 128 can be implemented by implanting p-type impurities in the absorber layer. 106 to achieve. Similarly, in some embodiments, the p-type doped region 128 may It is completely formed in the n-type well area 154. In certain other embodiments, the p-type doped region 138 may be partially formed in the n-type well region 154.

FIG. 1C shows a schematic diagram of a dual-switch photodiode 170 used to convert an optical signal into an electrical signal. The dual-switch photodiode 170 is similar to the dual-switch diode 100 shown in FIG. 1A, but the absorption layer 106 of the dual-switch photodiode 170 further includes an n-type well region 156. In addition, the absorption layer 106 may be a p-type doped region. In some embodiments, the doping level of the n-type well region 156 may be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 . The doping degree of the absorption layer 106 can be 10 ¹⁴ cm ³ to 10 ¹⁶ cm ^-3 .

The arrangement of the p-type doped region 128, the n-type well region 156, and the p-type doped region 138 forms a PNP junction structure. Generally speaking, the PNP junction structure can reduce the conduction current from the first control signal 122 to the second control signal 132 or selectively reduce the conduction current from the second control signal 132 to the first control signal 122. The arrangement of the n-type doped region 126, the p-type doped absorption layer 106, and the n-type doped region 136 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 124 to the second readout circuit 134, or selectively reduce the charge coupling from the second readout circuit 134 to the first readout circuit 124 . In some embodiments, if the depth of the n-type well region 156 is deep enough, the n-type doped region 126, the p-type doped region 106, the n-type well region 156, the p-type doped absorption layer 106, and the n-type doped region The arrangement of the regions 136 can form a NPNPN junction structure, thereby further reducing a charge coupling from the first readout circuit 124 to the second readout circuit 134, or selectively reduces the flow from the second readout circuit 134 to the first The charge of the readout circuit 124 is coupled.

In some embodiments, the p-type doped regions 128 and 138 may be completely formed in the n-type well region 156. In some embodiments, the p-type doped regions 128 and 138 may be partially formed in the n-type well District 156. For example, a part of the p-type doped region 128 can be implemented by implanting p-type impurities in the n-type well region 156, and another part of the p-type doped region 128 can be implemented by implanting p-type impurities in the absorption Layer 106 to achieve.

FIG. 1D shows a schematic diagram of a dual-switch photodiode 180 used to convert optical signals into electrical signals. The dual-switch photodiode 180 is similar to the dual-switch photodiode 100 shown in FIG. 1A, but the dual-switch photodiode 180 further includes a p-type well 104 and n-type wells 142 and 144. In some embodiments, the doping level of the n-type well regions 142 and 144 can be from 10 ¹⁶ cm ^-3 to 10 ²⁰ cm ^-3 , and the doping level of the p-type well region 104 can be from 10 ¹⁶ cm ^-3 to 10 ²⁰ cm ^-3 .

In some embodiments, the absorption layer 106 may not absorb all photons in the incident optical signal 112. For example, if the germanium-silicon platform does not absorb all the photons in the incident NIR optical signal 112, the NIR optical signal 112 can enter the silicon substrate 102; the silicon substrate 102 can absorb the photons that penetrate the substrate and produce deep recombination. These photocarriers with slower recombination will have a negative reaction to the operating speed of the dual-switch photodiode.

In order to remove the aforementioned slower recombination photocarriers, the dual-switch photodiode 180 may include contacts that short-circuit the n-type well regions 142 and 144 and the p-type well region 104. For example, the aforementioned contacts may be connected to the p-type well region 104 and the n-type well regions 142, 144 by using a silicide process or deposited metal pads. The short circuit between the n-type well regions 142, 144 and the p-type well region 104 allows photocarriers generated in the substrate 102 to recombine on the short-circuit contacts, thereby increasing the operating speed of the dual-switch photodiode. In some embodiments, the p-type well region 104 is used to reduce the electric field surrounding the interface defect between the absorber layer 106 and the substrate 102, thereby reducing device leakage current.

Although not shown in FIGS. 1A-1D, in some embodiments, the optical signal may reach the dual-switch photodiode from the backside of the substrate 102 of the dual-switch photodiode. One or more optical elements can be fabricated on the back side of the substrate 102 to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 1A-1D, in some embodiments, the first switch 108 and the second switch 110 can be selectively manufactured to collect holes instead of electrons. Under the aforementioned conditions, the p-doped region 128 and the p-type doped region 138 can be replaced by an n-type doped region, and the n-type doped region 126 and the n-type doped region 136 can be replaced by a p-type doped region. The n-type well regions 142, 144, 152, 154, and 156 can be replaced by p-type well regions, and the p-type well region 104 can be replaced by n-type well regions.

Although not shown in FIGS. 1A-1D, in some embodiments, the absorption layer 106 can be bonded to a substrate after the dual-switch photodiodes 100, 160, 170, and 180 are fabricated. The substrate can be any material that allows the photoelectric signal 112 to be transmitted to the dual-switch photodiode. For example, the substrate may be polymer or glass. In some embodiments, one or more optical elements can be fabricated on the carrier substrate to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 1A-1D, in some embodiments, the dual-switch photodiodes 100, 160, 170, and 180 can be used (for example, metal-to-metal bonding, oxide-to-oxide bonding, mixed Bonding) and bonding with a second substrate; the second substrate may have a control signal circuit and/or a readout circuit and/or a phase lock loop (PLL) and/or an analog-to-digital converter. A metal layer can be deposited on the top of the dual-switch photodiode to act as a reflector to reflect the light signal incident from the back side. An oxide layer can be provided between the metal layer and the absorption layer to increase the reflectivity. The metal layer can also be used as the bonding layer during the wafer bonding process. In some embodiments, one or more switches similar to the first switch 108 and the second switch 110 may be added to engage the control signal/readout circuit.

Although not shown in FIGS. 1A-1D, in some embodiments, the absorption layer 106 may be partially or completely embedded or recessed in the substrate 102 to ease the surface topography and facilitate fabrication. The aforementioned technology is disclosed in a patent application named "Germanium-Silicon Light Sensing Apparatus" in US Patent Application No. 15/228,282.

FIG. 2A shows a schematic diagram of a dual-switch photodiode 200 used to convert an optical signal into an electrical signal. In FIG. 2A, the first switch 208 and the second switch 210 are fabricated on a substrate 202. The double-switch photodiode 200 includes an absorption layer 206 which is fabricated on the substrate 202. The substrate 202 can be any substrate suitable for fabricating a semiconductor device thereon; for example, the substrate 202 can be a silicon substrate.

Generally, the absorption layer 206 receives an optical signal 212 and converts it into an electrical signal. The absorption layer 206 is similar to the absorption layer 106. In some embodiments, the absorption layer 206 may include a p-type doped region 209. The p-type doped region 209 can repel the photoelectrons from the absorption layer 206 to the substrate 202, thereby increasing the operating speed. For example, the p-type doped region 209 may have p+ doping. The p+ doping concentration can be the highest impurity concentration that can be achieved by the process; for example, when the absorption layer 206 is germanium and the impurity is boron, the highest p+ doping concentration is 5× ^{10 20} cm ⁻³ . In some embodiments, the doping concentration of the p-type doped region 209 can be lower than 5× ^{10 20} cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance.

The first switch 208 and the second switch 210 can be fabricated in the substrate 202. The first switch 208 is coupled to a first control signal 222 and a first readout circuit 224. The second switch 210 is coupled to a second control signal 232 and a second readout circuit 234. The first control signal 222 and the second control signal 232 control the first readout circuit 224 or the second readout circuit 234 to collect electrons or holes generated by the absorption of photons. The first control signal 222 is similar to the first control signal 122, the second control signal 232 is similar to the second control signal 132; the first readout circuit 224 is similar to the first readout circuit 124, and the second readout circuit 234 is similar to the first Two readout circuit 134.

In some embodiments, the first switch 208 and the second switch 210 can be used to collect the complex electrons generated by the absorption layer 206. Under the aforementioned conditions, the first switch 208 includes a p-type doped region 228 and an n-type doped region 226. For example, the p-type doped region 228 may have a p+ doping; wherein the activation impurity concentration of the p+ doping is the maximum doping concentration that can be achieved by the process, for example, when the substrate 202 is a silicon substrate and the impurity is boron , The highest concentration of p+ doping is 2x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the p-type doped region 228 can be lower than 2×10 ²⁰ cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The n-type doped region 226 may have an n+ doping; wherein the activation impurity concentration of the n+ doping is the maximum doping concentration that can be achieved by the process, for example, when the substrate 202 is a silicon substrate and the impurity is phosphorus, the n+ doping The highest concentration is 5x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the n-type doped region 226 can be lower than 5× ^{10 20} cm ⁻³ , thereby simplifying the manufacturing complexity while increasing the contact resistance. The distance between the p-type doped region 228 and the n-type doped region 226 can be designed according to process conditions. The shorter the distance between the p-type doped region 228 and the n-type doped region 226, the higher the switching efficiency of generating photocarriers. The second switch 210 includes a p-type doped region 238 and an n-type doped region 236. The p-type doped region 238 is similar to the p-type doped region 228, and the n-type doped region 236 is similar to the n-type doped region 226.

In some embodiments, the p-type doped region 228 is coupled to the first control signal 222. The n-type doped region 226 is coupled to the readout circuit 224. The p-type doped region 238 is coupled to the second control signal 232. The n-type doped region 236 is coupled to the readout circuit 234. The first control signal 222 and the second control signal 232 are used to control the collection of electrons generated by the absorption of photons. For example, the absorption layer 206 absorbs the complex number of photons in the optical signal 212 and generates electron-hole pairs, which drift or diffuse into the substrate 202. When a voltage is applied, if the first control signal 222 is different from the second control signal 232, an electric field will be established between the p-type doped region 228 and the p-type doped region 238, and free electrons will move from the absorber layer according to the direction of the electric field. 206 drifts toward the p-type doped region 228 or the p-type doped region 238. In some embodiments, the first control signal 222 may be fixed at a voltage value Vi, and the second control signal may alternate between the voltage value Vi±ΔV. The bias value determines the direction of electron drift. Accordingly, when one of the switches (for example, the first switch 208) is turned on (that is, electrons drift to the p-type doped region 228), the other switch (for example, the second switch 210) is turned off (that is, the electrons are doped by the p-type The miscellaneous area 238 is blocked). In some embodiments, the first control signal 222 and the second control signal 232 may have different voltage values.

In the first switch 208, an electric field is established between the p-type doped region 228 and the n-type doped region 226. Similarly, in the second switch 210, an electric field is established between the p-type doped region 238 and the n-type doped region 236. When the first switch 208 is turned on and the second switch 210 is turned off, electrons are attracted by the p-type doped region 228, and the electric field between the p-type doped region 228 and the n-type doped region 226 further allows the electrons to be doped to the n-type Zone 226 passes. The readout circuit 224 can then be The reason is that the charges collected in the n-type doped region 226 are collected. Conversely, when the second switch 210 is turned on and the first switch 208 is turned off, electrons are attracted by the p-type doped region 238, and the electric field between the p-type doped region 238 and the n-type doped region 236 further allows the electrons to move toward the n-type doped region. The type doped region 236 is transferred. The readout circuit 234 may then be able to process the charge collected by the n-type doped region 236.

In some embodiments, a voltage may be applied between the p-type doped region and the n-type doped region of a switch to allow the switch to operate in a sudden collapse mechanism to increase the sensitivity of the dual-switch photodiode 200. For example, when the distance between the p-type doped region 228 and the n-type doped region 229 is about 100 nanometers, a voltage lower than 7 volts can be applied to the p-type doped region 228 and the n-type doped region 228 Create sudden collapse gain between areas 226.

In some embodiments, the p-type doped region 209 can be coupled to an external control 214. For example, the p-type doped region 209 can be coupled to the ground. In some embodiments, the p-type doped region 209 may be floating or not coupled to any external control. In some embodiments, the substrate 202 can be coupled to an external control 216; for example, the substrate 202 can be coupled to ground. In some embodiments, the substrate 202 may be floating or not coupled to any external control.

FIG. 2B shows a schematic diagram of a dual-switch photodiode 250 used to convert an optical signal into an electrical signal. The dual-switch photodiode 250 is similar to the photodiode 200 shown in FIG. 2A, but the first switch 208 and the second switch 210 of the dual-switch photodiode 250 further include an n-type well 252 and a n-type well area 254. In addition, the absorption layer 206 may be a p-type doped region, and the substrate 202 may be a p-type doped substrate. In some embodiments, the doping level of the n-type well regions 252 and 254 can be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 . The doping level of the absorption layer 206 and the substrate 202 can be 10 ¹⁴ cm ^-3 to 10 ¹⁶ cm ^-3 .

The arrangement of the p-type doped region 228, the n-type well region 252, the p-type doped substrate 202, the n-type well region 254, and the p-type doped region 238 forms a PNPNP junction structure. Generally speaking, the PNPNP junction structure can reduce the conduction current from the first control signal 222 to the second control signal 232, or selectively reduce the conduction current from the second control signal 232 to the first control signal 222. The arrangement of the n-type doped region 226, the p-type doped substrate 202, and the n-type doped region 236 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 224 to the second readout circuit 234, or selectively reduce the charge coupling from the second readout circuit 234 to the first readout circuit 224 .

In some embodiments, the p-type doped region 228 is completely formed in the n-type well region 252. In some embodiments, the p-type doped region 228 may be partially formed in the n-type well region 252. For example, a part of the p-type doped region 228 can be implemented by implanting p-type impurities in the n-type well region 252, and another part of the p-type doped region 228 can be implemented by implanting p-type impurities in the n-type well region 252. Implementation in the substrate 202. Similarly, in some embodiments, the p-type doped region 238 may be completely formed in the n-type well region 254. In some embodiments, the p-type doped region 238 may be partially formed in the n-type well region 254.

FIG. 2C shows a schematic diagram of a dual-switch photodiode 260 used to convert optical signals into electrical signals. The dual-switch photodiode 260 is similar to the dual-switch photodiode 200 shown in FIG. 2A, but the substrate 202 of the dual-switch photodiode 260 further includes an n-type well 244. In addition, the absorption layer 206 may be a p-type doped region, and the substrate 202 may be a p-type doped substrate. In certain embodiments, the doping level of the n-type well region 244 may be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3, the absorbent layer 206 and the substrate 202 doping level may be 10 ¹⁴ cm ^-3 to 10 ¹⁶ cm ^{- 3} .

The arrangement of the p-type doped region 228, the n-type well region 244, and the p-type doped region 238 forms a PNP junction structure. The PNP junction structure can reduce the conduction current from one of the first control signal 222 to the second control signal 232, or can selectively reduce the conduction current from the second control signal 232 to the first control signal 222. The arrangement of the n-type doped region 226, the p-type doped substrate 202, and the n-type doped region 236 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 224 to the second readout circuit 234, or can selectively reduce the charge from the second readout circuit 234 to the first readout circuit 224 coupling. In some embodiments, if the depth of the n-type well region 244 is deep enough, the n-type doped region 226, the p-type doped substrate 202, the n-type well region 244, the p-type doped substrate 202, and the n-type doped region The arrangement of 236 can form a NPNPN junction structure to further reduce the charge coupling from the first readout circuit 224 to the second readout circuit 234, or can selectively reduce the charge coupling from the second readout circuit 234 to the second readout circuit 234. Charge coupling of a readout circuit 224. In some embodiments, the n-type well region 244 can effectively reduce the potential energy barrier that electrons can perceive when flowing from the absorption layer 206 to the substrate 202.

In some embodiments, the p-type doped regions 228 and 238 are completely located in the n-type well region 244. In some embodiments, the p-type doped regions 228 and 238 may be partially formed in the n-type well region 244; for example, a part of the p-type doped region 228 may be implanted by p-type impurities in the n-type well region. In the region 244, another part of the p-type doped region 228 can be realized by implanting p-type impurities in the substrate 202.

2D shows a schematic diagram of a dual-switch photodiode 270 used to convert an optical signal into an electrical signal. The dual-switch photodiode 270 is similar to the dual-switch photodiode 200 shown in FIG. 2A, but the dual-switch photodiode 270 further includes one or more p-type well regions 246 and one or more p-type wells. District 248. In some embodiments, the one or more p-type well regions 246 and the one or more p-type well regions 246 may be part of a ring structure that surrounds the first switch 208 and the second switch 210 . In some embodiments, the doping level of the p-type well regions 246 and 248 can be 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 . The aforementioned one or more p-type well regions 246 and 248 are used to separate the complex photoelectrons of adjacent pixels.

Although not shown in FIGS. 2A-2D, in some embodiments, an optical signal may be incident on the backside of the substrate 202 of the dual-switch photodiode. One or more optical components may be fabricated on the back side of the substrate 202 to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 2A-2D, in some embodiments, the first switch 208 and the second switch 210 can be selectively manufactured to collect holes instead of electrons; under the aforementioned conditions, The p-type doped region 228, the p-type doped region 238, and the p-type doped region 209 can be replaced by an n-type doped region, and the n-type doped region 226 and the n-type doped region 236 can be replaced by a p-type doped region. , The n-type well regions 252, 254, and 244 can be replaced by p-type well regions, and the p-type well regions 246 and 248 can be replaced by n-type well regions.

Although not shown in FIGS. 2A-2D, in some embodiments, after the dual-switch photodiodes 200, 250, 260, and 270 are fabricated, the absorption layer 209 may be bonded to a substrate. The carrier substrate can be any material that allows the optical signal 212 to be transmitted to the dual-switch photodiode. For example, one or more optical elements can be fabricated on the carrier substrate to focus, collimate, defocus, filter, or perform other functions on the optical signal 212.

Although not shown in FIGS. 2A-2D, in some embodiments, the dual-switch photodiodes 200, 250, 260, and 270 can be used (for example, metal-to-metal bonding, oxide For oxide bonding, hybrid bonding) and bonding with a second substrate; the second substrate has a circuit for control signals and/or a readout circuit and/or a phase-locked loop and/or an analog-to-digital converter. A metal layer can be deposited on the top of the dual-switch photodiode to act as a reflector to reflect the light signal incident from the back side. An oxide layer can be provided between the metal layer and the absorption layer to increase the reflectivity. The metal layer can also be used as the bonding layer during the wafer bonding process. In some embodiments, one or more switches similar to the first switch 208 and the second switch 210 may be added to engage the control signal/readout circuit.

Although not shown in FIGS. 2A-2D, in some embodiments, the absorption layer 206 may be partially or completely embedded or recessed in the substrate 202 to ease the surface topography and facilitate fabrication. The aforementioned technology is disclosed in a patent application named "Germanium-Silicon Light Sensing Apparatus" in US Patent Application No. 15/228,282.

FIG. 3A shows a schematic diagram of a dual-switch photodiode 300 used to convert an optical signal into an electrical signal. In FIG. 3A, the first switches 308a and 308b, and the second switches 310a and 310b are vertically fabricated on a substrate 302. One feature of the double-switch photodiode 100 or the double-switch photodiode 200 is that it has a large optical window size d. The electrons drift or diffuse from one switch to the other switch have a long transmission time of photoelectrons, which will affect the photoelectricity. The operating speed of the diode. The dual-switch photodiode 300 can further increase the operating speed by vertically arranging the p-type doped region and the n-type doped region. With the vertical arrangement, the photoelectron transmission distance is reduced from the original optical window size d (for example, about 10 μm) of the absorption layer to the thickness t (for example, about 1 μm) of the absorption layer. Double switch photodiode 300 It includes an absorption layer 306, which is fabricated on a substrate 302. The substrate 302 can be any suitable substrate for fabricating a semiconductor device thereon, such as a silicon substrate.

Generally, the absorption layer 306 receives an optical signal 312 and converts the optical signal 312 into a complex electrical signal. The absorption layer 306 is similar to the absorption layer 206. In some embodiments, the absorption layer 306 may include a p-type doped region 309, which is similar to the p-type doped region 209.

The first switches 308a and 308b and the second switches 310a and 310b are all fabricated in the substrate 302. It should be noted here that although FIG. 3A only shows two first switches 308a and 308b and two second switches 310a and 310b, the number of first switches and second switches is not limited to this. The first switches 308a and 308b are coupled to a first control signal 322 and a first first readout circuit 324. The second switches 310a and 310b can be coupled to a second control signal 332 and a second readout circuit 334.

Generally speaking, the first control signal 322 and the second control signal 332 control the electrons or holes collected by the first readout circuit 324 or the second readout circuit 334, and the aforementioned electrons or holes are absorbed by the absorption layer 306. Generated by photons. The first control signal 322 is similar to the first control signal 122, the second control signal 332 is similar to the second control signal 132, the first readout circuit 324 is similar to the first readout circuit 124, and the second readout circuit 334 is similar to the first Two readout circuit 134. In some embodiments, the first switches 308 a and 308 b and the second switches 310 a and 310 b can be fabricated to collect electrons generated by the absorption layer 306. Under such conditions, the first switches 308a and 308b respectively include p-type doped regions 328a, 328b and n-type doped regions 326a, 326b. For example, the p-type doped regions 328a and 328b may have a p+ doping; wherein, the activation impurity concentration may be the highest impurity concentration achievable by the process. For example, when the substrate 302 is silicon and the impurity is boron, p+ doping The highest concentration can be 2x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the p-type doped regions 328a and 328b can be lower than 2×10 ²⁰ cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The n-type doped regions 326a and 326b may have an n+ doping; wherein, the activation impurity concentration may be the highest impurity concentration achievable by the process. For example, when the substrate 302 is silicon and the impurity is phosphorus, the highest n+ doping concentration may be It is 5x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the n-type doped regions 326a and 326b can be lower than 5× ^{10 20} cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The distance between the p-type doped region 328a and the n-type doped region 326a can be designed according to process conditions. For example, the distance between the p-type doped region 328a and the n-type doped region 326a can be controlled according to the energy of the implanted impurities. Generally speaking, as the distance between the p-type doped regions 328a/328b and the n-type doped regions 326a/326b is closer, the switching efficiency for generating photocarriers is higher. The second switches 310a and 310b include p-type doped regions 338a and 338b, and n-type doped regions 336a and 336b, respectively. The p-type doped regions 338a/338b are similar to the p-type doped regions 328a/328b, and the n-type doped regions 336a/336b are similar to the n-type doped regions 326a/326b.

In some embodiments, the p-type doped regions 328 a and 328 b are coupled to the first control signal 322. The n-type doped regions 326a and 326b are coupled to the readout circuit 324. The p-type doped regions 338a and 338b can be coupled to the second control signal 332. The n-type doped regions 336a and 336b are coupled to the readout circuit 334. The first control signal 322 and the second control signal 332 are used to control the collection of electrons generated by the absorbed photons. For example, when the absorption layer 306 absorbs photons in the optical signal 312, the generated electron-hole pairs drift or diffuse to the substrate 302. When voltage is applied, if the first control signal 322 is different from the second control signal 332. A complex electric field will be established between the p-type doped region 309 and the p-type doped region 328a/328b or the p-type doped region 338a/338b, and the electrons from the absorber layer 306 will move toward the p-type according to the direction of the electric field. The doped regions 328a/328b or the p-type doped regions 338a/338b drift. In some embodiments, the first control signal 322 may be fixed at a voltage value Vi, and the second control signal 332 may alternate between the voltage value Vi±ΔV. The direction of the bias value determines the drift direction of electrons. Thereby, when a group of switches (for example, the first switches 308a and 308b) are turned on (that is, electrons drift to the p-type doped regions 328a and 328b), another switch (for example, the second switches 310a and 310b) is turned off (that is, the electrons Blocked by p-type doped regions 338a and 338b). In some embodiments, the first control signal 322 and the second control signal 332 may have different voltage values.

In each of the first switches 308a/308b, an electric field is established between the p-type doped regions 328a/328b and the n-type doped regions 326a/326b. Similarly, in each of the second switches 310a/310b, an electric field is established between the p-type doped regions 338a/338b and the n-type doped regions 336a/336b. When the first switches 308a and 308b are turned on and the second switches 310a and 310b are turned off, electrons are attracted by the p-type doped regions 328a and 328b, and the electric field between the p-type doped region 328a and the n-type doped region 326a is further increased The electrons are transferred to the n-type doped region 326a; similarly, the electric field between the p-type doped region 328b and the n-type doped region 326b also allows electrons to be transferred to the n-type doped region 326b. The readout circuit 324 can then process the charges collected by the n-type doped regions 326a and 326b. Conversely, when the second switches 310a and 310b are turned on and the first switches 308a and 308b are turned off, electrons are attracted by the p-type doped regions 338a and 338b. The electric field further allows electrons to pass to the n-type doped region 336a; similarly, the gap between the p-type doped region 338b and the n-type doped region 336b The electric field also allows electrons to pass to the n-type doped region 336b. The readout circuit 334 can then process the charges collected by the n-type doped regions 336a and 336b.

In some embodiments, a voltage can be applied between the p-type doped region and the n-type doped region of a switch to allow the switch to operate in the breakdown region to increase the sensitivity of the dual-switch photodiode 300. For example, when the distance between the p-type doped region 328a and the n-type doped region 326a is about 100 nm, a voltage lower than 7 volts can be applied to the p-type doped region 328a and the n-type doped region 328a A sudden collapse gain is created between areas 326a.

In some embodiments, the p-type doped region 309 can be coupled to an external control 314; for example, the p-type doped region 309 can be coupled to ground. In some embodiments, the p-type doped region 309 may be floating or not coupled to any external control. In some embodiments, the substrate 302 can be coupled to an external control 316; for example, the substrate 302 can be coupled to ground. In some embodiments, the substrate 302 may be floating or not coupled to any external control.

FIG. 3B shows a schematic diagram of a dual-switch photodiode 360 used to convert an optical signal into an electrical signal. The dual-switch photodiode 360 is similar to the dual-switch photodiode 360 shown in FIG. 3A, but the dual-switch photodiode 360 further includes an n-type well region 344. In addition, the absorption layer 306 may be a p-type doped region, and the substrate may be a p-type doped substrate. In some embodiments, the doping degree of the n-type well region 344 can be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 , and the doping degree of the substrate 302 can be 10 ¹⁴ cm ³ to 10 ¹⁶ cm ^-3 .

The arrangement of the p-type doped region 328a, the n-type well region 344 and the p-type doped region 338a forms a PNP junction structure; similarly, the p-type doped region 328b, the n-type well region 344 and the p-type doped region 338b Also arranged in a PNP junction structure. Generally speaking, the PNP junction structure can reduce the conduction current from the first control signal 322 to the second control signal 332, or can be selectively The ground reduces the conduction current from the second control signal 332 to the first control signal 322. The arrangement of the n-type doped region 326a, the p-type doped substrate 302, and the n-type doped region 336a forms an NPN junction structure; similarly, the n-type doped region 326b, the p-type doped substrate 302, and the n-type doped region Region 336b is also arranged in an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 324 to the second readout circuit 334, or can selectively reduce the charge coupling from the second readout circuit 334 to the first readout circuit 324. Charge coupled. In some embodiments, the n-type well region 344 can effectively reduce the potential energy barrier that electrons can perceive when flowing from the absorber layer 306 to the substrate 302.

In some embodiments, the p-type doped regions 328a, 338a, 328b, and 338b are completely formed in the n-type well region 344. In some embodiments, the p-type doped regions 328a, 338a, 328b, and 338b may be partially formed in the n-type well region 344. For example, a part of the p-type doped region 328a can be realized by implanting p-type impurities in the n-type well region 344, and another part of the p-type doped region 328a can be realized by implanting p-type impurities on the substrate 302. To achieve.

FIG. 3C shows a schematic diagram of a dual-switch photodiode 370 used to convert an optical signal into an electrical signal. The dual-switch photodiode 370 is similar to the dual-switch photodiode 30 shown in FIG. 3A, but the dual-switch photodiode 370 further includes one or more p-type well regions 346 and one or more p-type wells. District 348. In some embodiments, the one or more p-type well regions 346 and the one or more p-type well regions 348 may be part of a ring structure that surrounds the first switch 308a, 308b and the second switch 308a, 308b. Switches 310a, 310b. In some embodiments, the doping level of one or more p-type well regions may range from 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 . The aforementioned one or more p-type well regions 346 and 348 are used to separate the complex photoelectrons of adjacent pixels.

FIG. 3D shows a cross-sectional view of a dual-switch photodiode 380. In FIG. 3D, the p-type doped regions 328a and 328b of the first switches 308a and 308b, and the p-type doped regions 338a and 338b of the second switches 310a and 310b may be arranged crosswise on a first plane 362 of the substrate 302 superior. FIG. 3D further illustrates that the n-type doped regions 326a and 326b of the first switches 308a and 308b, and the n-type doped regions 336a and 336b of the second switches 310a and 310b can be arranged crosswise on a second plane of the substrate 302 364.

Although not shown in FIGS. 3A-3D, in some embodiments, the optical signal can reach the dual-switch photodiode from the substrate 302 on the back side of the dual-switch photodiode. One or more optical elements can be fabricated on the back side of the substrate 302 to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 3A-3D, in some embodiments, the first switches 308a and 308b, and the second switches 310a and 310b can be selectively fabricated to collect holes instead of electrons. Under the aforementioned conditions, the p-type doped regions 328a and 328b, the p-type doped regions 338a and 338b, and the p-type doped region 309 can be replaced with n-type doped regions, the n-type doped regions 326a and 326b, and The n-type doped regions 336a and 336b can be replaced by p-type doped regions, the n-type well region 344 can be replaced by p-type well regions, and the p-type well regions 346 and 348 can be replaced by n-type well regions.

Although not shown in FIGS. 3A-3D, in some embodiments, after the dual-switch photodiodes 300, 360, 370, and 380 are fabricated, the absorption layer 306 may be bonded to a substrate. The carrier substrate can be any material that allows the optical signal 312 to be transmitted to the dual-switch photodiode. For example, one or more optical elements can be fabricated on the carrier substrate to focus, collimate, defocus, filter, or perform other functions on the optical signal 312.

Although not shown in FIGS. 3A-3D, in some embodiments, the dual-switch photodiodes 300, 360, 370, and 380 can be (for example, metal-to-metal bonding, oxide-to-oxide bonding, mixed Bonding) to bond with a second substrate; the second substrate may have a control signal circuit and/or a readout circuit and/or a phase-locked loop and/or an analog-to-digital converter. A metal layer can be deposited on the top of the dual-switch photodiode to act as a reflector to reflect the light signal incident from the back side. An oxide layer can be provided between the metal layer and the absorption layer to increase the reflectivity. The metal layer can also be used as the bonding layer during the wafer bonding process. In some embodiments, one or more switches similar to the first switch 308a (or 308b) and the second switch 310a (or 310b) may be added to engage the control signal/readout circuit.

Although not shown in FIGS. 3A-3D, in some embodiments, the absorption layer 306 may be partially or completely embedded or recessed in the substrate 302 to ease the surface topography and facilitate fabrication. The aforementioned technology is disclosed in a patent application named "Germanium-Silicon Light Sensing Apparatus" in US Patent Application No. 15/228,282.

4A shows a schematic diagram of a dual-switch photodiode 400 used to convert an optical signal into an electrical signal. The double-switch photodiode 400 includes an absorption layer 406, and the absorption layer 406 is fabricated on a substrate 402. The substrate 402 can be any substrate suitable for fabricating a semiconductor device on it, for example, a silicon substrate. The absorption layer 406 includes a first switch 408 and a second switch 410.

Generally, the absorption layer 406 receives an optical signal 412 and converts the optical signal 412 into a complex electrical signal. The absorption layer 406 can be selected to have a high absorption rate for the demand band. For Near-Infrared (NIR) wavelengths, the absorption layer 406 can be a germanium silicon platform; Among them, the germanium silicon absorbs the photons in the light signal 412 and generates electron-hole pairs. In the germanium silicon platform, the content of germanium and silicon can be adjusted according to a specific process or application. In some embodiments, the absorption layer 406 is designed to have a thickness t. For example, for a wavelength of 850nm, the germanium silicon platform is about 1 micron, so that it has substantial quantum efficiency. In some embodiments, the surface of the absorption layer 406 is designed to have a special shape. For example, the shape of the germanium silicon mesa can be circular, square or rectangular according to the spatial distribution of the optical signal 412 on the germanium silicon mesa. In some embodiments, the absorption layer 406 may be designed to have a lateral dimension to receive the optical signal 412. For example, the germanium silicon mesa can be circular, and its lateral dimension d can range from 1 micrometer to 50 micrometers.

The first switch 408 and the second switch 410 are fabricated in the absorption layer 406 and the substrate 402. The first switch 408 is coupled to a first control signal 422 and a first readout circuit 424. The second switch 410 is coupled to a second control signal 432 and a second readout circuit 434. Generally, the first control signal 422 and the second control signal 432 control the electrons or holes generated by the absorption of photons collected by the first readout circuit 424 or the second readout circuit 434.

In some embodiments, the first switch 408 and the second switch 410 are designed to collect electrons. Under the aforementioned conditions, the first switch 408 includes a p-type doped region 428 and an n-type doped region 426. The p-type doped region 428 is implanted in the absorber layer 406, and the n-type doped region 426 is implanted on the substrate. 402 in. For example, the p-type doped region 428 may have a p+ doping, the activation impurity concentration of which is the highest impurity concentration achievable by the process; for example, when the absorber layer 106 is germanium and the impurity is boron, the highest concentration of p+ doping It can be 5x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the p-type doped region 428 can be lower than 5× ^{10 20} cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The n-type doped region 426 may have an n+ doping, and its activation impurity concentration is the highest impurity concentration achievable by the process; for example, when the substrate 402 is silicon and the impurity is phosphorus, the maximum n+ doping concentration may be 5x10 ²⁰ cm ^-3 . In some embodiments, the doping concentration of the n-type doped region 426 can be lower than 5× ^{10 20} cm ⁻³ , so as to simplify the manufacturing complexity while increasing the contact resistance. The distance between the p-type doped region 428 and the n-type doped region 426 can be designed according to the process conditions; in general, the closer the distance between the p-type doped region 428 and the n-type doped region 426, the more complex The switching efficiency of photocarriers is higher. The second switch 410 includes a p-type doped region 438 and an n-type doped region 436, the p-type doped region 438 is similar to the p-type doped region 428, and the n-type doped region 436 is similar to the n-type doped region 426.

In some embodiments, the p-type doped region 428 is coupled to the first control signal 422. For example, the p-type doped region 48 can be coupled to a voltage source; wherein, the first control signal 422 can provide an AC voltage signal for the voltage source. In some embodiments, the n-type doped region 426 is coupled to the readout circuit 424. The readout circuit 424 can be a tri-transistor structure composed of a reset gate, a source follower, and a select gate or other circuits for processing free carriers. In some embodiments, the readout circuit 424 can be fabricated on the substrate 402. In some embodiments, the readout circuit 424 can be fabricated on another substrate and form a common package with the dual-switch photodiode 400 using chip/wafer bonding or stacking technology.

The p-type doped region 438 is coupled to the second control signal 432. For example, the p-type doped region 438 can be coupled to a voltage source; wherein, the second control signal 462 can provide an AC voltage signal for the voltage source, and its phase is opposite to the first control signal 422. In some implementations In the formula, the n-type doped region 436 is coupled to the readout circuit 434, and the readout circuit 434 can be similar to the readout circuit 424.

The first control signal 422 and the second control signal 432 are used to control the collection of electrons generated by the absorption of photons. For example, when a voltage is applied, if the first control signal 422 is different from the second control signal 432, an electric field is established between the p-type doped region 428 and the p-type doped region 438, and the free electrons depend on the direction of the electric field. And drift to the p-type doped region 428 or the p-type doped region 438. In some embodiments, the first control signal 422 may be fixed at a voltage value Vi, and the second control signal 432 may alternate between the voltage value Vi±ΔV. The direction of the bias value determines the drift direction of electrons. When one switch (for example, the first switch 408) is turned on (that is, electrons drift to the p-type doped region 428), the other switch (for example, the second switch 410) is turned off (that is, the electrons are blocked by the p-type doped region 438) . In some embodiments, the first control signal 422 and the second control signal 432 may have different voltage values.

Generally speaking, the Fermi level difference between a p-type doped region and an n-type doped region will establish an electric field between the two regions. In the first switch 408, an electric field is established between the p-type doped region 428 and the n-type doped region 426; similarly, in the second switch 410, an electric field is established between the p-type doped region 438 and the n-type doped region Between the doped regions 436. When the first switch 408 is turned on and the second switch 410 is turned off, electrons are attracted by the p-type doped region 428, and the electric field in the p-type doped region 428 and the n-type doped region 426 further allows the electrons to go to the n-type doped region. 426 passed. The readout circuit 424 can then process the charges collected by the n-type doped region 426. On the other hand, when the second switch 410 is turned on and the first switch 408 is turned off, electrons are attracted by the p-type doped region 438, and the electric field between the p-type doped region 438 and the n-type doped region 436 further allows The electrons are transferred to the n-type doped region 436. The readout circuit 434 may then process the charges collected by the n-type doped region 436.

In some embodiments, the substrate 402 is coupled to an external control 416. For example, the substrate 402 can be coupled to the ground. In some embodiments, the substrate 402 may be floating or not coupled to any external control.

4B shows a schematic diagram of a dual-switch photodiode 450 used to convert an optical signal into an electrical signal. The dual-switch photodiode 450 is similar to the dual-switch photodiode 400 shown in FIG. 4A, but the first switch 408 and the second switch 410 further include an n-type well region 452 and an n-type well region 454, respectively. In addition, the absorption layer 406 may be a p-type doped layer, and the substrate 402 may be a p-type doped substrate. In some embodiments, the doping level of the n-type well region 452 can be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ³ , and the doping level of the substrate 402 can be 10 ¹⁴ cm ^-3 to 10 ¹⁶ cm ³ .

The arrangement of the p-type doped region 428, the n-type well region 452, the p-type doped absorber layer 406, the n-type well region 454, and the p-type doped region 438 forms a PNPNP junction structure. Generally speaking, the PNPNP junction structure can reduce a conduction current from the first control signal 422 to the second control signal 432, or can selectively reduce the conduction current from the second control signal 432 to the first control signal 422.

The arrangement of the n-type doped region 426, the p-type doped substrate 402, and the n-type doped region 436 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 424 to the second readout circuit 434, or can selectively reduce the charge from the second readout circuit 434 to the first readout circuit 424 coupling.

In some embodiments, the p-type doped region 428 may be completely formed in the n-type well region 452. In some embodiments, the p-type doped region 428 may be partially formed in the n-type well region 452; for example, a part of the p-type doped region 428 may be implanted by p-type impurities in the n-type well region 452. To achieve this, another part of the p-type doped region 128 can be achieved by implanting p-type impurities in the absorption layer 406. Similarly, in some embodiments, the p-type doped region 428 may be completely formed in the n-type well region 454. In some embodiments, the p-type doped region 438 may be partially formed in the n-type well region 454.

4C shows a schematic diagram of a dual-switch photodiode 460 used to convert an optical signal into a telecommunication. The dual-switch photodiode 460 is similar to the dual-switch diode 400 shown in FIG. 4A, but the dual-switch photodiode 460 further includes an n-type well region 456. In addition, the absorption layer 406 may be a p-type doped region, and the substrate 402 may be a p-type doped substrate. In some embodiments, the doping level of the n-type well region 456 may be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 . The doping level of the absorption layer 406 and the substrate 402 can be 10 ¹⁴ cm ³ to 10 ¹⁶ cm ^-3 .

The arrangement of the p-type doped region 428, the n-type well region 456 and the p-type doped region 438 forms a PNP junction structure. Generally speaking, the PNP junction structure can reduce the conduction current from the first control signal 422 to the second control signal 432, or can selectively reduce the conduction current from the second control signal 432 to the first control signal 422.

The arrangement of the n-type doped region 426, the p-type doped absorption layer 406, and the n-type doped region 436 forms an NPN junction structure. Generally speaking, the NPN junction structure can reduce the charge coupling from the first readout circuit 424 to the second readout circuit 434, or can selectively reduce the charge from the second readout circuit 434 to the first readout circuit 424 coupling.

In some embodiments, the p-type doped regions 428 and 438 may be completely formed in the n-type well region 456. In some embodiments, the p-type doped regions 428 and 438 may be partially formed in the n-type well region 456; for example, a part of the p-type doped region 428 may be implanted by p-type impurities in the n-type well. In the region 456, another part of the p-type doped region 428 can be realized by implanting p-type impurities in the absorption layer 406.

4D shows a schematic diagram of a dual-switch photodiode 470 used to convert an optical signal into an electrical signal. The double-switch photodiode 470 is similar to the double-switch photodiode 460 shown in FIG. 4C, but the n-type well region 458 of the double-switch photodiode 470 extends from the absorption layer 406 to the substrate 402. In addition, the absorption layer 406 may be a p-type doped region, and the substrate 402 may be a p-type doped substrate. In some embodiments, the doping level of the n-type well region 456 may be 10 ¹⁵ cm ^-3 to 10 ¹⁷ cm ^-3 . The doping level of the absorption layer 406 and the substrate 402 can be 10 ¹⁴ cm ^-3 to 10 ¹⁶ cm ^-3 .

The arrangement of the p-type doped region 428, the n-type well region 458 and the p-type doped region 438 forms a PNP junction structure, which can further reduce a conduction current from the first control signal 422 to the second control signal 432. Or, the conduction current from the second control signal 432 to the first control signal 422 can be selectively reduced. The n-type doped region 426, the p-type doped substrate 402 and the n-type well region 458, the p-type doped substrate 402 and the n-type doped region 436 form an NPNPN junction structure, thereby reducing the number of first readout circuits The charge coupling from 424 to the second readout circuit 434 or the charge coupling from the second readout circuit 434 to the first readout circuit 424 can be selectively reduced. In some embodiments, the n-type well region 458 can effectively reduce the potential energy barrier that electrons can perceive when flowing from the absorber layer 406 to the substrate 402.

4E shows a schematic diagram of a dual-switch photodiode 480 used to convert an optical signal into an electrical signal. The dual-switch photodiode 480 is similar to the dual-switch photodiode 400 shown in FIG. 4A, but the dual-switch photodiode 480 further includes one or more p-type well regions 446 and one or more p-type wells. District 448. In some embodiments, the one or more p-type well regions 446 and the one or more p-type well regions 448 may be part of a ring structure that surrounds the first switch 408 and the second switch 410 . In some embodiments, the doping level of the p-type well regions 446 and 448 may be 10 ¹⁵ cm ^-3 to 10 ²⁰ cm ^-3 . The aforementioned one or more p-type well regions 446 and 448 are used to separate the complex photoelectrons of adjacent pixels.

Although not shown in FIGS. 4A-4E, in some embodiments, the optical signal can reach the dual-switch photodiode from the backside of the substrate 402 of the dual-switch photodiode. One or more optical elements can be fabricated on the back side of the substrate 402 to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 4A-4E, in some embodiments, the first switch 408 and the second switch 410 can be selectively manufactured to collect holes instead of electrons. Under the aforementioned conditions, the p-type doped region 428 and the p-type doped region 438 can be replaced by an n-type doped region, and the n-type doped region 426 and the n-type doped region 436 can be replaced by a p-type doped region. , The n-type well regions 452, 454, 456, and 458 can be replaced by p-type well regions, and the p-type well regions 446 and 448 can be replaced by n-type well regions.

Although not shown in FIGS. 4A-4E, in some embodiments, the absorption layer 406 may be bonded to a substrate after the dual-switch photodiodes 400, 450, 460, 470, and 480 are fabricated. The substrate can be any material that allows the photoelectric signal 412 to be transmitted to the dual-switch photodiode. For example, the substrate may be polymer or glass. In some embodiments Among them, one or more optical elements can be fabricated on the carrier substrate to focus, collimate, defocus, filter, or perform other functions on the optical signal.

Although not shown in FIGS. 4A-4E, in some embodiments, the dual-switch photodiodes 400, 450, 460, 470, and 480 can be used (for example, metal-to-metal bonding, oxide-to-oxide bonding , Hybrid bonding) and bonding with a second substrate; the second substrate may have a control signal circuit and/or a readout circuit and/or a phase-locked loop and/or an analog-to-digital converter. A metal layer can be deposited on the top of the dual-switch photodiode to act as a reflector to reflect the light signal incident from the back side. An oxide layer can be provided between the metal layer and the absorption layer to increase the reflectivity. The metal layer can also be used as the bonding layer during the wafer bonding process. In some embodiments, one or more switches similar to the first switch 408 and the second switch 410 may be added to engage the control signal/readout circuit.

Although not shown in FIGS. 4A-4E, in some embodiments, the absorption layer 406 may be partially or completely embedded or recessed in the substrate 402 to ease the surface topography and facilitate fabrication. The aforementioned technology is disclosed in a patent application named "Germanium-Silicon Light Sensing Apparatus" in US Patent Application No. 15/228,282.

FIG. 5A shows a schematic diagram of an imaging system 500 used to determine the characteristics of a target object 510. The target object 510 may be a three-dimensional object. The image capturing system 500 may include a transmitting unit 502, a receiving unit 504, and a processing unit 506. Generally, the transmitting unit 502 emits light pulses 512 toward the target object 510; the transmitting unit 502 may include one or more light sources, control circuits, and/or optical elements. For example, the transmitting unit 502 may include One or more NIR light-emitting diodes or lasers; among them, the light pulse 512 can be collimated by a collimating lens and then transmitted to the free space.

The receiving unit 504 receives the reflected light pulse 514 reflected by the target object 510. The receiving unit 504 may include one or more photodiodes, control circuits, and/or optical elements. For example, the receiving unit 504 may include an image sensor; where the image sensor includes a plurality of pixels fabricated on a semiconductor substrate, and each pixel may include one or more multi-gate photodiodes for The reflected light pulse 514 is sensed, and the reflected light pulse 514 is focused on the dual-switch photodiode. Each double-switch photodiode can be the double-switch photodiode disclosed in the present invention.

The processing unit 506 processes the photocarriers generated by the receiving unit 504 and determines the characteristics of the target object 510. The processing unit 506 may include a control circuit, one or more processors, and/or a computing storage interface, where the computing storage interface is used to store instructions corresponding to the characteristics of the target object 510 sensed. For example, the processing unit 506 may include a readout circuit and a processor, where the processor may process information about photocarriers used to determine the characteristics of the target object 510. In some embodiments, the characteristic of the target object 510 may be the depth information of the target object 510. In some embodiments, the characteristic of the target object 510 may be the material composition of the target object 510.

；其中c為光速。 FIG. 5B shows a schematic diagram of a technique for determining the characteristics of a target object 510 according to the present invention. The transmitting unit 502 can generate a light pulse 512, wherein the light pulse 512 is modulated to have a frequency fm and a duty cycle of 50%. The receiving unit 504 can receive the reflected light pulse 514; the reflected light pulse 514 has a phase shift Φ. The double-switch electric diode is controlled to allow a first readout circuit to read the collected charge Q1, and a second readout circuit to read the collected charge Q2; wherein the charge Q1 and the light pulse have the same phase ( Synchronous), the charge Q2 has the opposite phase to the light pulse. In some embodiments, the distance D between the imaging system 500 and the target object 510 satisfies the following equation:

; Where c is the speed of light.

。 FIG. 5C shows a schematic diagram of another technique for determining the characteristics of a target object 510. The transmitting unit 502 can emit a light pulse 512; wherein the light pulse 512 is modulated to have a frequency fm and a duty cycle of 50%. By reducing the duty cycle of the light pulse 512 by a factor N, and increasing the intensity of the light pulse by this factor N, the received reflected light pulse can be maintained while maintaining substantially the same power loss of the imaging system 500 The signal-to-noise ratio of 514 is enhanced. This increases the bandwidth of the imaging system 500, thereby reducing the duty cycle of the light pulse without the pulse shape being distorted. The receiving unit 504 can receive the reflected light pulse 514; the reflected light pulse 514 has a phase shift Φ. The multi-gate photodiode is controlled so that a first readout circuit reads the collected charge Q1', and a second readout circuit reads the collected charge Q2'; wherein, the phase of the charge Q1' is the same as The phase of the light pulse, the phase of the charge Q2' is different from the phase of the light pulse. In some embodiments, the distance D between the imaging system 1800 and the target object 1810 satisfies the following equation:

.

FIG. 6 shows a flow chart of using an imaging system to sense the characteristics of an object. The process 600 may be executed on the imaging system 500, for example.

The system receives the reflected light (step 602). For example, the transmitting unit 502 can transmit a light pulse 512 in the NIR band to the target object 510. The receiving unit 504 receives the reflected light pulse 514 in the NIR band after being reflected by the target object 510.

The system determines the position information (step 604). For example, the receiving unit 504 may include an image sensor; where the image sensor includes a plurality of pixels fabricated on a semiconductor substrate. Each pixel may include one or more dual-switch photodiodes for sensing the reflected light pulse 514. The double-switch photodiode can be any double-switch photodiode disclosed in the present invention; wherein the phase information can be measured using the technique described in FIG. 5B or FIG. 5C.

The system determines the characteristics of the object (step 606). For example, the processing unit 506 may determine the depth information of the target object 510 according to the phase information technology as described in FIG. 5B or FIG. 5C.

In some embodiments, the image sensor includes a plurality of pixels, which are fabricated on a semiconductor substrate, and each pixel may include one or more dual-switch photodiodes 100, 160, 170, 180, 200, 250, 260, 270, 300, 360, 370, 380, 400, 450, 460, 470, and 480 to sense the reflected light shown in FIGS. 5A and 5B. Adjacent two pixels can be separated by insulators (such as oxide or nitride layers), separated by implants (such as using p+ or n+ regions to block electrons or holes), or intrinsically embedded in energy barriers (such as using germanium-silicon heterogeneous interface). accomplish.

Although the present disclosure has been described herein with reference to specific exemplary embodiments; however, it should be confirmed that the present invention is not limited to the described embodiments, on the contrary, It can also be implemented with amendments and alterations that fall within the spirit and scope of the attached patent application. For example, the previously disclosed process can be reordered, added or removed steps.

For ease of description and explanation, in many embodiments herein, a two-dimensional section is used as the basis for explanation; however, as long as there is a corresponding two-dimensional section in the three-dimensional structure, its three-dimensional change should also be included in the present invention. In the range.

Although this document contains many details, this is as a description of specific features of specific embodiments and should not be used to limit the present invention. Herein, certain features described in a single embodiment may be implemented only in a single embodiment, but the features described in a single embodiment may also be implemented in multiple embodiments alone or in combination.

Similarly, although operations in a specific order are described in the diagrams, these operations can be performed in other specific orders or sequential orders, or performed in the order of the diagrams to achieve the desired effect. Under certain conditions, multiple tasks or parallel processing can achieve specific advantages. In addition, different system elements may be separated from each other in different embodiments, but it should not be considered that these elements must be separated from each other in all embodiments.

Although specific embodiments of the present invention are described, other embodiments are still within the scope of the present invention. For example, the operations defined in the scope of the patent can be performed in a different order, and the desired effect can still be achieved.

100...Double switch photodiode 102...Substrate 106...absorbent layer 108...First switch 110...Second switch 112... Optical signal 116...External control 122...The first control signal 124...First readout circuit 132...Second control signal 134...Second readout circuit 126, 136...n-type doped region 128, 138...p-type doped regions

Claims (39)

An optical device comprising: a semiconductor substrate; a germanium silicon platform supported by the semiconductor substrate and in direct contact with the semiconductor substrate, the germanium silicon platform including a photodiode region, the photodiode region for absorbing One or more first switches are controlled by a first control signal, and the one or more first switches collect at least a part of the first control signal according to the first control signal. Photocarriers; and one or more second switches controlled by a second control signal, and the one or more second switches collect at least a part of the photocarriers according to the second control signal, wherein the first A control signal is different from the second control signal, wherein the one or more first switches include: a first p-type doped region located in the germanium silicon platform, and the first control signal controls the first p-type doped region; and a first n-type doped region located in the germanium silicon platform, the first n-type doped region is coupled to a first readout integrated circuit; wherein, the one or The plurality of second switches includes: a second p-type doped region located in the germanium silicon platform, the second control signal controls the second p-type doped region; and a second n-type doped region located in the silicon germanium platform In the germanium silicon platform, the second n-type doped region is coupled to a second readout integrated circuit. The optical device described in claim 1, The silicon germanium platform includes a third n-type doped region and a fourth n-type doped region, wherein at least a part of the first p-type doped region is formed in the third n-type doped region, and wherein At least a part of the second p-type doped region is formed in the fourth n-type doped region. The optical device according to claim 1, wherein the germanium silicon platform includes a third n-type doped region, and wherein at least a part of the first p-type doped region and at least a part of the second p-type doped region Formed in the third n-type doped region. The optical device according to claim 1, wherein the semiconductor substrate includes a third p-type doped region and one or more n-type doped regions, wherein the germanium silicon platform is disposed above the third p-type doped region . In the optical device according to claim 4, the third p-type doped region is short-circuited to the one or more n-type doped regions. An optical device comprising: a semiconductor substrate including a recess; a germanium silicon platform at least partially embedded in the recess and in direct contact with the semiconductor substrate, the germanium silicon platform including a photodiode region, the photoelectric The diode region is used to absorb multiple photons and generate multiple photocarriers; one or more first switches are controlled by a first control signal, and the one or more first switches are Collecting at least a part of the photocarriers; and one or more second switches controlled by a second control signal, and the one or more second switches collect at least a part of the photocarriers according to the second control signal Equal photocarriers, where the first control signal is different from the second control signal, Wherein, the one or more first switches include: a first p-type doped region located in the germanium silicon platform, the first control signal controls the first p-type doped region; and a first n Type doped region located in the germanium-silicon platform, the first n-type doped region is coupled to a first readout integrated circuit; wherein, the one or more second switches include: a second p Type doped region located in the silicon germanium platform, the second control signal controls the second p-type doped region; and a second n-type doped region located in the silicon germanium platform, the second n-type doped region The miscellaneous region is coupled to a second readout integrated circuit. The optical device according to claim 6, wherein the germanium-silicon platform includes a third n-type doped region and a fourth n-type doped region, wherein at least a part of the first p-type doped region is formed in the first Among the three n-type doped regions, at least a part of the second p-type doped region is formed in the fourth n-type doped region. The optical device according to claim 6, wherein the germanium-silicon platform includes a third n-type doped region, and wherein at least a part of the first p-type doped region and at least a part of the second p-type doped region Formed in the third n-type doped region. The optical device according to claim 6, wherein the semiconductor substrate includes a third p-type doped region and one or more n-type doped regions, wherein the germanium silicon platform is disposed above the third p-type doped region . In the optical device according to claim 9, the third p-type doped region is short-circuited to the one or more n-type doped regions. A time difference ranging system includes: a light source for generating a plurality of photons; and an image sensor including a plurality of pixels, the pixels are supported by a semiconductor substrate, wherein each of the pixels includes: an absorbing layer, which is supported by a semiconductor substrate. Supported by a semiconductor substrate, the semiconductor substrate and the absorption layer comprise different material compositions, the absorption layer comprises a photodiode region, and the photodiode region is used to absorb the plurality of photons and generate a plurality of photocarriers; one or more A first switch, a first control signal controls the one or more first switches, and the one or more first switches collect at least a first part of the plurality of photocarriers according to the first control signal And one or more second switches, a second control signal controls the one or more second switches, and the one or more second switches collect at least a second part according to the second control signal Wherein the second control signal is different from the first control signal, and the complex photocarriers of the first part and the complex photocarriers of the second part are of the same type. The time difference ranging system according to claim 11, wherein the absorption layer includes a germanium silicon layer. The time difference ranging system according to claim 11, wherein the semiconductor substrate includes a silicon substrate. The time difference ranging system according to claim 11, wherein the one or more first switches are coupled to a first readout integrated circuit, and the one or more second switches are coupled to a second readout product Body circuit, wherein the light source is used to emit a plurality of light pulses, one of the light pulses has a duty cycle less than 50%, and during operation, the first readout integrated circuit reads collected by the one or more first switches The charge (Q1) of the second readout circuit reads the charge (Q2) collected by the one or more second switches; wherein, the charge (Q1) has the same phase as the light pulses, and the charge (Q2) ) Has the opposite phase to the light pulses. The time difference ranging system according to claim 14, wherein each of the light pulses has the same energy. The time difference ranging system according to claim 14, wherein the complex number of photons generated by the light source has an infrared light wavelength. An optical device, comprising: an absorption layer, comprising a photodiode region, the photodiode region is used to absorb a plurality of photons and generate a plurality of photocarriers; one or more first switches, controlled by a first Signal control. The one or more first switches collect at least a first part of the photocarriers according to the first control signal; and one or more second switches are controlled by a second control signal , The one or more second switches collect at least one second part of the photocarriers according to the second control signal, wherein the first control signal is different from the second control signal, and the first part of the The plurality of photocarriers and the plurality of photocarriers of the second part are of the same type; wherein, the one or more first switches include: a first well region having a first type; A first doped region having a second type opposite to the first type, at least a part of the first doped region is formed in the first well region, and the first doped region is formed by the first Control signal control; a second doped region having the first type and coupled to a first readout integrated circuit; and wherein the one or more second switches include: a second well Region, which has the first type; a third doped region, which has the second type, at least a part of the third doped region is formed in the second well region, and the third doped region Controlled by the second control signal; and a fourth doped region having the first type and coupled to a second readout integrated circuit. The optical device according to claim 17, wherein the first well area overlaps the second well area. The optical device according to claim 17, wherein the absorption layer includes the first well region and the second well region. The optical device according to claim 17, wherein the absorption layer includes the first doped region and the second doped region. The optical device according to claim 17, wherein the first type is n-type and the second type is p-type. The optical device according to claim 17, wherein the first type is p-type and the second type is n-type. A stereo imaging system, including: A transmitting unit including a light source for generating a plurality of photons and guiding the plurality of photons to a target object; a receiving unit including an image sensor including a plurality of pixels supported by a silicon substrate, Each pixel of the plurality of pixels includes an absorption layer, which includes a different material composition from the silicon substrate, and the absorption layer includes a photodiode region for absorbing a plurality of the photons and generating A plurality of photocarriers; wherein each of the plurality of pixels is set to be at least partially reflected by the target object and the photons can be transmitted to the photodiode region of the absorption layer by the silicon substrate; wherein the absorption layer Substantially absorb photons in the near-infrared light region, and the silicon substrate generally absorbs photons in a shorter wavelength region than the near-infrared light region. The stereoscopic imaging system according to claim 23, wherein the complex photons generated by the light source have a wavelength that is not absorbed or partially absorbed by the silicon substrate. According to the three-dimensional imaging system of claim 23, the light source includes a light emitting diode or a laser. The stereoscopic imaging system according to claim 23 further includes a processing unit for processing the photocarriers generated by the receiving unit and determining the characteristics of the target object. The three-dimensional imaging system according to claim 23, wherein the characteristic of the target object includes depth information or a material composition information. An optical device, comprising: a semiconductor substrate having a first material composition; An absorption layer, which is supported by the semiconductor substrate and has a second material composition different from the first material composition, wherein the absorption layer is used to absorb incident light in the first wavelength band and generate plural photocarriers; The first switch is coupled to the absorption layer and includes: a first terminal for receiving a first control signal; and a second terminal for collecting at least Part of the plurality of photocarriers; and a first readout circuit, which is coupled to the second terminal of the first switch, for reading the collected by the second terminal of the first switch Photocarrier. The optical device according to claim 28, wherein the first material composition includes silicon. The optical device of claim 28, wherein the second material composition includes germanium. The optical device according to claim 28, wherein the first wavelength band includes near-infrared light. The optical device according to claim 28, further comprising a metal layer on the absorption layer. The optical device according to claim 28, wherein the first terminal includes a first p-type doped region, and the second terminal includes a first n-type doped region. The optical device according to claim 33, wherein the entire first p-type doped region or a part of the first p-type doped region is formed in an n-type well region. The optical device according to claim 28, wherein the absorption layer is embedded in the semiconductor substrate. An optical system, comprising: a light source for generating complex photons in a first waveband; and An image sensor including a plurality of pixels supported by a semiconductor substrate, the semiconductor substrate having a first material composition, wherein each pixel of the plurality of pixels includes: an absorption layer supported by the semiconductor substrate and having A composition of a second material that is different from the composition of the first material, wherein the absorption layer is used to absorb incident light in the first wavelength band and generate a plurality of photocarriers; one or more first switches are combined with a first An integrated circuit is coupled to and controlled by a first control signal, and each of the one or more first switches collects at least a first part of the plurality of photocarriers according to the first control signal; And one or more second switches, which are coupled to a second integrated circuit and controlled by a second control signal, and each of the one or more second switches is controlled according to the second control signal The signal collects at least a second portion of the complex photocarriers; wherein the complex photocarriers of the first portion and the complex photocarriers of the first portion are of the same type. The optical system according to claim 36, wherein the second material composition includes germanium. The optical system according to claim 36, further comprising a metal layer on the absorption layer. The optical system according to claim 36, wherein the absorption layer is embedded in the semiconductor substrate.

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