TWI419347B - Pin photodiode structure and method for making the same - Google Patents

Description

PIN light diode structure and preparation method thereof

The present invention relates to a photodiode structure and a method of fabricating the same. In particular, it relates to a light-sensitive PIN light diode structure and a method of manufacturing the same.

As the amount of information transmitted by the message increases, the required transmission distance is also farther and farther. Due to the inherent physical limitations of resistance and signal lag, the traditional copper cable is no longer suitable for such load. Since a plurality of beams of different wavelengths in a single fiber respectively carry different information, the signals are transmitted at the speed of light without mutual interference, and the signals are not excessively attenuated by the extremely long distance signals, and meet the long-distance transmission requirements for satisfying a large amount of information. Fiber optics has naturally become the most important long-distance information transmission medium.

However, different wavelengths of light combined with pulse signals constitute the basic principle of optical fiber communication. However, these basic transmission principles are incompatible with the transmission principle of electronic flow carrying and transmitting signals in today's electronic devices. In order to form a conversion medium between fiber communication and current communication, a photo-detector becomes a convenient and useful tool.

A photodetector is an important photo-electronic conversion component. Light detector In order to convert the optical pulse signal into an electrical signal (voltage or current), the optical pulse signal in the optical fiber can be converted into an electronic signal that can be carried, transmitted and utilized by general electronic components. Among them, a PIN photodiode (p-intrinsic-n photodiode) which is easy to manufacture, has high reliability, low noise, can be matched with a low voltage amplifier circuit, and has extremely high frequency and wide characteristics is a commonly used photodetector. .

The basic working principle of the PIN photodiode is that when the incident photon is irradiated on the p-n junction of the semiconductor, if the photon energy is sufficiently large, the electrons of the valence band in the semiconductor material can absorb the energy of the photon. The valence band passes over the forbidden band to reach the conductive strip, that is, the incident photon will generate electrons in the conductive strip of the semiconductor, called photoelectron, and also leave a hole in the valence band, that is, generate an electron. An electron-hole pair, also known as photocarriers, is the photoelectric effect of a semiconductor. Thereafter, the photoelectrons and the holes are quickly separated by the built-in electric field and an externally applied negative bias, and the positive and negative electrodes are collected separately, and the photocurrent appears in the external circuit.

In order to enhance the operational efficiency of the PIN photodiode, the current technology integrates germanium semiconductor materials into germanium substrates to achieve wide-wavelength optical communication, which is believed to be due to the carrier mobility of germanium being much higher than that of germanium. The importance of the integration of germanium semiconductor materials into germanium substrates lies in the important characteristics of fast, efficient and low noise.锗Photodetector has a wavelength that can be utilized in optical communication Effectively detect the nature of optical signals within the range. In addition, if the 光 photodetector can be integrated with the traditional process of the ruthenium substrate, it should be able to further reduce the cost of the PIN photodiode.

A PIN light-detecting diode for integrating a germanium semiconductor material into a germanium substrate is known. FIG. 1 illustrates that the known PIN-detecting diode PIN light-detecting diode 101 containing a germanium-containing semiconductor material includes a germanium substrate. 110, an oxide layer 120, a P-doped germanium 130, an intrinsic Ge 140, an N-doped germanium 150, an electrode region including a first electrode region 161 and a second electrode region 162. P-doped germanium 130, intrinsic germanium 140, and N-doped germanium 150 together constitute a core component of the PIN light-detecting diode. Since the structure of the above PIN light-detecting diode 101 is in the electrode doping region The first electrode region 161 is disposed above the N-doped germanium 150, thereby reducing the range of front side light receiving, and the light is absorbed when passing through the P-doped germanium to reduce the quantum efficiency, and the PIN light detecting second The fabrication process of the polar body 101 is not fully integrated with the conventional MOS process. Therefore, a novel PIN light-detecting diode structure and a manufacturing method are needed, which can more effectively integrate the process with the traditionally developed metal-oxygen semiconductor process to achieve the goal of reducing manufacturing cost.

Therefore, the present invention proposes a novel PIN optical diode structure and Production method. The manufacturing process can be more effectively integrated with the traditionally developed MOS process to achieve the goal of reducing manufacturing costs to solve the above problems.

The invention first relates to a PIN light diode structure. The PIN photodiode structure of the present invention comprises a semiconductor substrate containing germanium, a P-type doped region in the semiconductor substrate, an N-type doped region in the semiconductor substrate, and in the semiconductor substrate and in the P-type a doped region and a first semiconductor material of an N-type doping region. Preferably, the first semiconductor material comprises germanium or has a germanium concentration gradient.

The invention further provides a method of forming a PIN photodiode structure. The method of the present invention for forming a PIN photodiode structure first provides a semiconductor substrate comprising an N-type doped region and a P-type doped region. Secondly, a trench is formed in the semiconductor substrate between the P-type doped region and the N-type doped region. Thereafter, the trench is filled with the first semiconductor material such that the first semiconductor material can also be raised from the trench. Preferably, the first semiconductor material comprises germanium or has a germanium concentration gradient.

Due to the PIN photodiode structure of the present invention, both the P-type doped region and the N-type doped region used as the conductive electrode are located in the substrate of the semiconductor, so the method for fabricating the novel PIN light-detecting diode structure of the present invention can be Increasing the range of light received and more effectively making its process and traditionally developed The process of cooked MOS is fully integrated to achieve the goal of reducing manufacturing costs.

The present invention relates to a novel PIN photodiode structure and a method of fabricating the same. Due to the PIN photodiode structure of the present invention, both the P-type doped region and the N-type doped region used as the conductive electrode are located in the substrate on both sides of the germanium semiconductor material, so that the novel PIN optical diode structure of the present invention is fabricated. The method not only can greatly increase the range of light receiving, but also can more effectively integrate its process with the process of the traditionally mature metal oxide semiconductor to achieve the goal of reducing manufacturing costs.

The present invention first provides a photodiode structure. Fig. 2 illustrates a preferred embodiment of the photodiode structure of the present invention. The photodiode structure 200 of the present invention comprises a semiconductor substrate 201, a shallow trench isolation (STI) 210, a P-doped region 221, an N-type doped region 222, a trench 230, and an interlayer dielectric layer 240. P-type doped region plug plug 251 and N-type doped region plug 252.

The semiconductor substrate 201 can be a general semiconductor material such as a substrate such as tantalum or silicon-on-insulator (SOI). The insulating material of the shallow trench isolation 210 or the like is located in the semiconductor substrate 201 to distinguish different component regions. As shown in Figure 2 As shown, the periphery of the photodiode structure 200 of the present invention is provided with a shallow trench isolation 210.

The trench 230 is also located in the semiconductor substrate 201 surrounded by the shallow trench isolation 210. In addition, opposite sides of the trench 230 are respectively provided with a P-type doping region 221 and an N-type doping region 222 which are also located in the semiconductor substrate 201. The P-doped region 221 and the N-type doped region 222 may be formed in the semiconductor substrate 201 using conventional dopants in combination with conventional ion implantation. In addition, a thermal diffusion or annealing step may be added to activate the P-type doping region 221 and the N-type doping region 222.

The first semiconductor material 231 is located in the trench 230 and fills the trench 230. Since the position of the trench 230 is in the semiconductor substrate 201 and is between the P-type doping region 221 and the N-type doping region 222, the first semiconductor material 231 is also located in the semiconductor substrate 201, and at the same time The P-type doped region 221 is between the N-type doped region 222. The first semiconductor material 231 can be a general semiconductor material such as tantalum, niobium, or combinations thereof. Preferably, the first semiconductor material 231 has a germanium concentration gradient.

In addition, a second semiconductor material 232 connected to the first semiconductor material 231 and protruding from one of the surfaces of the first semiconductor material 231 may be additionally disposed on the first semiconductor material 231. The second semiconductor material 232 can be a general semiconductor material such as tantalum, niobium, or combinations thereof. Preferably, these second The semiconductor material 232 has a germanium concentration gradient that is inherited from the first semiconductor material 231 concentration gradient.

The interlayer dielectric layer 240 covers the semiconductor substrate 201, the P-doped region 221, the N-type doped region 222, the trench 230, the first semiconductor material 231, and the second semiconductor material 232. Also, the interlayer dielectric layer 240 has a P-type doped region plug 251, that is, located on the P-type doped region 221 to establish a subsequent electrical connection between the P-type doped region 221 and other stacks. Similarly, an N-type doped region plug 252 is located in the interlayer dielectric layer 240 on the N-type doped region 222 to establish a subsequent electrical connection between the N-type doped region 222 and other stacks. The P-type doping region plug 251 and the N-type doping region plug 252 may each use a conventional conductive material such as aluminum or tungsten. Optionally, the surface of the P-doped region 221 and the N-type doped region 222 may further comprise a metal telluride such as cobalt telluride or nickel telluride to reduce the P-type doped region plugs 251 and N. The surface resistance of the doped region plug 252 for the P-type doped region 221 and the N-type doped region 222.

The semiconductor substrate 201 of the present invention may further comprise at least one metal oxide semiconductor (MOS), if desired. In other words, the adjacent region of the photodiode structure 200 may be provided with a complementary metal oxide semiconductor 260 (CMOS). Fig. 3 illustrates a preferred embodiment in which a complementary metal oxide semiconductor is disposed next to the photodiode structure of the present invention. As shown in FIG. 3, adjacent regions of the photodiode structure 200 of the present invention are provided with complementary P-type MOS 261 and N-type gold oxide. The semiconductors 262 are each insulated by a shallow trench isolation 210.

Moreover, in order to be sufficiently compatible with the MOS process, the components of the photodiode structure 200 of the present invention can share some of the process characteristics with the components of the complementary MOS 260. For example, at least one of the P-doped region 221 and the N-type doped region 222 of the photodiode structure 200 of the present invention may have a doping concentration of a plurality of doped regions such as a source/drain of the complementary MOS 260. The doping concentration is the same.

It should be noted that the photodiode structure 200 of the present invention may have different light receiving directions. For example, in the case of the structure illustrated in Fig. 2, the photodiode structure 200 of the present invention can be used to receive a top incident light. On the other hand, the photodiode structure 200 of the present invention can also be applied to receive a side incident light. Fig. 4 illustrates a preferred embodiment of the photodiode structure of the present invention for receiving a side light source. The light diode structure 200 of the present invention further comprises a light guide 270 for receiving the light source from the side, so that the light diode structure of the present invention is equally suitable for accepting the upper light source or receiving the side light source or accepting simultaneously. .

The invention further provides a method of forming a photodiode structure. Figures 5-9 illustrate a preferred embodiment of the method of forming a photodiode of the present invention. First, as shown in FIG. 5, a semiconductor substrate 501 including a P-type doping region 521 and an N-type doping region 522 is provided. The semiconductor substrate 501 can be a General semiconductor materials, such as germanium. The oxide layer 502 covers the surface of the semiconductor substrate 501. A metal oxide semiconductor may be further included on the semiconductor substrate 501. For example, the semiconductor substrate 501 is further provided with a complementary MOS semiconductor 560 including a complementary P-type MOS 561 and an N-type MOS 562, each of which is insulated by a shallow trench isolation 510.

In order to be sufficiently compatible with the MOS process, the components of the photodiode structure of the present invention can share some of the process characteristics with the components of the complementary MOS 560. For example, a conventional dopant may be used in combination with a conventional ion implantation method to simultaneously form a P-doped region 521 and an N-type doped region 522 in the photodiode structure of the present invention in forming a complementary MOS semiconductor 560. In addition, a thermal diffusion or annealing step may be added to activate the P-doped region 521 and the N-type doped region 522. When the P-type doping region 521 and the N-type doping region 522 are simultaneously formed with the complementary gold-oxygen semiconductor 560, at least one of the doping concentration of the P-type doping region 521 and the N-type doping region 522 may be complementary to the complementary MOS semiconductor. The doping concentrations of the various doping regions such as the source/drain of 560 are the same.

Next, as shown in FIG. 6, a trench 530 is formed in the semiconductor substrate 501 and between the P-doped region 521 and the N-type doped region 522. For example, after the position of the trench 530 is defined using a conventional photoresist, a portion of the semiconductor substrate 501 is removed by etching to form a trench 530.

Next, as shown in FIG. 7, using the first semiconductor material 531 Full ditch 530. The first semiconductor material 531 is a general semiconductor material such as germanium, germanium, or a combination thereof. For example, the first semiconductor material 531 is filled with the trench 530 using a conventional epitaxial process. Preferably, the first semiconductor material 531 is a mixture of cerium and lanthanum and has a cerium concentration gradient. As a result, the problem of mismatching with the lattice of the germanium-containing semiconductor substrate 501 can be effectively avoided.

In a preferred embodiment, the second semiconductor material 532 on the first semiconductor material 531 and protruding from the surface of the semiconductor substrate 501 can be continuously epitaxially formed in the epitaxial process of the first semiconductor material 531 to receive the upper light source. Or side light source. The second semiconductor material 532 can be a general semiconductor material such as germanium, germanium, or combinations thereof. Preferably, the second semiconductor material 532 has a germanium concentration gradient that is inherited from the first semiconductor material 531 concentration gradient.

After the step of FIG. 7 is completed, as shown in FIG. 8, the interlayer dielectric layer 540 is further formed to cover the semiconductor substrate 501, the P-type doped region 521, the N-type doped region 522, the first semiconductor material 531 and the second Semiconductor material 532. In addition, in order to form an electrical connection, a contact hole is also formed to accommodate the P-type doped region plug 551 and the N-type doped region plug 552. Optionally, a surface of the P-doped region 521 and the N-type doped region 522 may be further formed with a metal halide such as cobalt telluride or nickel telluride to reduce the P-type doped region plug 551 and N-type doped region plug 552 for P type The surface resistance of the doped region 521 and the N-type doped region 522.

As described above, the photodiode fabricated by the method of the present invention can have different light receiving directions. For example, in the case of the structure illustrated in Fig. 8, the photodiode structure of the present invention is suitable for receiving an upper light source. On the other hand, the photodiode structure of the present invention can also be used for receiving a side light source, which is illustrated by the method of the present invention. A preferred embodiment of a photodiode structure that can be used to form a side light source. In the photodiode structure of the present invention, the first semiconductor material 531 and the side of the second semiconductor material 532 further form a light guide 570 for guiding the light source of the present invention to receive the light source from the side, so that The photodiode structure produced by the method of the invention is equally suitable for accepting an upper source or accepting a side source or simultaneously.

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

101‧‧‧PIN Detector Diode

110‧‧‧矽 substrate

120‧‧‧Oxide layer

130‧‧‧P-doped 矽

140‧‧‧ inherent

150‧‧‧N-doping

161‧‧‧First electrode zone

162‧‧‧second electrode zone

200‧‧‧Light diode structure

201‧‧‧Semiconductor substrate

210‧‧‧Shallow trench isolation

221‧‧‧P-doped area

222‧‧‧N-doped area

230‧‧‧ Ditch

231‧‧‧First semiconductor material

232‧‧‧Second semiconductor material

240‧‧‧Interlayer dielectric layer

251‧‧‧P-type doped area plug

252‧‧‧N type doped area plug

260‧‧‧Complementary MOS

261‧‧‧P type MOS

262‧‧‧N type MOS

270‧‧‧Light Guide

501‧‧‧Semiconductor substrate

510‧‧‧Shallow trench isolation

521‧‧‧P-doped area

522‧‧‧N-doped area

530‧‧‧ Ditch

531‧‧‧First semiconductor material

532‧‧‧Second semiconductor material

540‧‧‧Interlayer dielectric layer

551‧‧‧P-type doped area plug

552‧‧‧N type doped area plug

560‧‧Complementary MOS

561‧‧‧P type MOS

562‧‧‧N type MOS

570‧‧‧Light Guide

Fig. 1 illustrates a conventional light-detecting diode of a germanium-containing material.

Fig. 2 illustrates a preferred embodiment of the photodiode structure of the present invention.

Fig. 3 illustrates a preferred embodiment in which a complementary metal oxide semiconductor is disposed next to the photodiode structure of the present invention.

Figure 4 illustrates one of the photodiode structures of the present invention for receiving a side light source Preferred embodiment.

Figures 5-9 illustrate a preferred embodiment of the method of forming a photodiode of the present invention.

200‧‧‧Light diode structure

201‧‧‧Semiconductor substrate

210‧‧‧Shallow trench isolation

221‧‧‧P-doped area

222‧‧‧N-doped area

230‧‧‧ Ditch

231‧‧‧First semiconductor material

232‧‧‧Second semiconductor material

240‧‧‧Interlayer dielectric layer

251‧‧‧P-type doped area plug

252‧‧‧N type doped area plug

Claims (21)

A PIN photodiode structure comprising: a semiconductor substrate comprising germanium; a P-type doped region located in the semiconductor substrate; an N-type doped region located in the semiconductor substrate; a semiconductor material disposed in the semiconductor substrate and between the P-type doped region and the N-type doped region; and a second semiconductor material in contact with and connected to the first semiconductor material The surface of the material, the second semiconductor material is a semiconductor. The PIN photodiode structure of claim 1, wherein the second semiconductor material comprises germanium. The PIN photodiode structure of claim 1, further comprising: an interlayer dielectric layer covering the semiconductor substrate, the P-type doped region, the N-type doped region and the first semiconductor material; a dummy pad pluged in the interlayer dielectric layer on the P-type doped region and electrically connected to the P-type doped region; and an N-type doped region plug on the N-type doped region The interlayer dielectric layer is electrically connected to the N-type doped region. The PIN photodiode structure of claim 1, wherein the first semiconductor material comprises ruthenium and iridium. The PIN photodiode structure of claim 1, wherein the first semiconductor material has a concentration gradient of one 。. The PIN photodiode structure of claim 1, wherein the semiconductor substrate comprises at least one metal oxide semiconductor (MOS). The PIN photodiode structure of claim 6, wherein at least one of a doping concentration of the P-type doping region and the N-type doping region is the same as a doping concentration of a source/drain of the MOS semiconductor. The PIN photodiode structure of claim 3, further comprising two sets of metal germanides, respectively located between the P-type doped region plug and the P-type doped region, and the plug in the N-type doped region Between the N-type doped regions. The PIN light diode structure of claim 1 is for receiving a top incident light. The PIN light diode structure of claim 9 further comprising a light guide for directing a side incident light. A method of forming a PIN photodiode structure, comprising: providing a semiconductor substrate comprising an N-type doped region and a P-type doped region; forming a trench in the semiconductor substrate and the P-type doping Zone with the N Between the doped regions; and filling the trench with a first semiconductor material. The method of claim 11, further comprising: forming a second semiconductor material on the first semiconductor material and protruding the surface of the semiconductor substrate, wherein the second semiconductor material comprises germanium. The method of claim 12, wherein the second semiconductor material is for receiving a top incident light. The method of claim 11, further comprising: forming an interlevel dielectric layer covering the semiconductor substrate, the P-type doped region, the N-type doped region, the first semiconductor material and the trench; and between the layers Forming a P-type doped region plug and an N-type doped region plug in the dielectric layer, respectively located on the P-type doped region and electrically connected to the P-type doped region and located in the N-type doping The impurity region is electrically connected to the N-type doping region. The method of claim 11, wherein the first semiconductor material comprises ruthenium and osmium. The method of claim 11, wherein the first semiconductor material has a concentration gradient of one turn. The method of claim 11, wherein the semiconductor substrate comprises at least one complementary metal oxide semiconductor (CMOS). The method of claim 17, wherein the doping concentration of the P-type doping region and the doping concentration of the N-type doping region are the same as those of the complementary oxy-semiconductor. The method of claim 11, further comprising: forming a metal halide on the P-type doping region and the N-type doping region, respectively. The method of claim 11, wherein the first semiconductor material is for receiving a side incident light. The method of claim 20, further comprising: forming a light guide for guiding the side light source.