阅读说明：本技术 一种碳化硅横向jfet器件及其制备方法 (silicon carbide transverse JFET (junction field Effect transistor) device and preparation method thereof ) 是由 温正欣 叶怀宇 张新河 陈施施 张国旗 于 2019-10-22 设计创作，主要内容包括：本发明属于半导体器件技术领域,公开了一种碳化硅横向JFET器件结构。其主要结构包括一N+衬底,在其上方依次为一P+隔离层,一P-层,一N-漂移区。在N-漂移区的上方左侧有两个P+栅区,两个P+栅区通过N-沟道区隔开,在N-沟道区顶部为N+源极接触区。一N-第二漂移区,位于P+栅区右侧,一N+漏区位于N-第二漂移区右侧顶部,两个栅极,一源极,一漏极分别位于前述P+栅区、N+源极接触区和N+漏极接触区之上。本发明还提供了制备该碳化硅横向JFET器件制备的工艺方法,利用沟槽外延方法,减小了器件工艺成本和难度。(The invention belongs to the technical field of semiconductor devices, and discloses an silicon carbide transverse JFET device structure, which mainly comprises a N + substrate, wherein a P + isolation layer, a P-layer and a N-drift region are sequentially arranged above the substrate, two P + grid regions are arranged on the left side above the N-drift region, the two P + grid regions are separated by an N-channel region, an N + source contact region, a N-second drift region are arranged at the top of the N-channel region and are positioned on the right side of the P + grid region, an N + drain region is positioned at the top of the right side of the N-second drift region, and two grid electrodes, a source electrode and a drain electrode are respectively positioned on the P + grid region, the N + source contact region and the N + drain electrode contact region.)

A lateral JFET device of kinds of silicon carbide, which is characterized by comprising

N + substrate (1), which is provided with a P + isolation layer (2), a P-layer (3) and a N-drift region (4) in sequence above the substrate, wherein the left side above the N-drift region (4) is provided with two P + gate regions (5), the two P + gate regions (5) are separated by an N-channel region (7), and the top of the N-channel region (7) is provided with an N + source contact region (8);

N-second drift region (6) located at the right side of the P + gate region, N + drain region (9) located at the top of the right side of the N-second drift region (6), and gate (10), source (11) and drain (12) located above the P + gate region (5), N + source contact region (8) and N + drain contact region (9), respectively.

2. Silicon carbide lateral JFET device according to claim 1, wherein the P + isolation layer (2) has a thickness of 0.2-1 μm and a doping concentration of 5 x 10¹⁶cm^-3-5×10¹⁷cm^-3(ii) a The thickness of the P-layer (3) is 1-5 μm, and the doping concentration is 1 x 10¹⁵cm^-3-2×10¹⁶cm^-3(ii) a The thickness of the N-drift region (4) is 5-20 μm, and the doping concentration is 2 x 10¹⁴cm^-3-1×10¹⁶cm^-3。

3. The lateral silicon carbide JFET device of claim 1, wherein the P + gate region (5) has a doping concentration of 5 x 10¹⁸cm^-3Above, the thickness is 0.5 μm-5 μm; the thickness of the N-second drift region (6) is the same as the height of the P + gate region (5), and the doping concentration is the same as that of the N-drift region (4).

4. The lateral silicon carbide JFET device of claim 1, wherein the N + source contact region (8) and the N + drain contact region (9) are ion implanted regions having a depth of 0.2-0.5 μm and a nitrogen doping concentration of 2 x 10¹⁸cm^-3-5×10¹⁹cm^-3。

5. The silicon carbide lateral JFET device of claim 1, wherein: the grid electrode 10 forms ohmic contact with the P + grid region (5), and the grid electrode material comprises Ti/TaSi₂Pt; the source electrode (11) and the drain electrode (12) form ohmic contact with the N + source electrode contact region (8) and the N + drain region (9) respectively, and the source electrode material is TaSi₂/Pt。

A method of fabricating lateral JFET devices in silicon carbide, comprising the steps of:

s1: sequentially growing a P +/P-/N-/P + type epitaxial layer on an N + type silicon carbide substrate;

s2: etching the surface of the epitaxial layer to form a gate region;

s3: epitaxially growing an N-type drift layer to fill the groove, and grinding, polishing and flattening the surface;

s4: ion implantation is carried out to form a source contact region and a drain contact region;

s5: and stripping to form the gate, source and drain metals.

7. The lateral JFET device manufacturing method according to claim 6, wherein the S3 process comprises cleaning the epitaxial wafer, epitaxially growing N-doped silicon carbide by using an HTCVD device, completely filling the trench, and then polishing to remove the N-type epitaxial layer covering the P + gate region (5) to form the N-channel region (7) and the N-second drift region (6).

8. The method of manufacturing lateral silicon carbide JFET devices of claim 6, wherein the S5 includes:

s5.1, cleaning the epitaxial wafer, coating glue, photoetching, developing, sputtering metal Ti, and soaking in an acetone solution to strip the metal Ti;

s5.2 coating, photoetching, developing and sputtering TaSi₂Pt, forming Ti/TaSi on the gate region (10) after stripping again₂a/Pt composite metal, TaSi is formed on the N + source contact region (8) and the N + drain contact region (9)₂the/Pt composite metal is annealed at 600 ℃ for 30 minutes to form ohmic contact.

Technical Field

The invention belongs to the technical field of semiconductor power devices, and particularly relates to silicon carbide transverse JFET devices and a preparation method thereof.

Background

Junction Field-Effect transistors (JFETs) are voltage control devices, and control of output drain-source current is realized by changing the conductivity of a channel by using the terminal voltage of a PN Junction, i.e., the gate-source voltage thereof.

The minority carrier lifetime of the silicon carbide JFET device is greatly influenced by temperature, and within a normal working temperature range, the minority carrier lifetime tends to rise along with the temperature change.

The silicon carbide JFET transverse device can be prepared on an N-type substrate, a P-type substrate and a semi-insulating substrate, the SiC JFET device prepared on the P-type substrate and the semi-insulating substrate has better performance generally, and the N-type substrate is compatible with the SiC longitudinal power device, so that the cost is lower.

Disclosure of Invention

() problems to be solved

The invention aims to provide silicon carbide JFET transverse devices aiming at the characteristics of silicon carbide materials, the devices are based on commercial N-type substrates, are convenient to transversely integrate, have simple preparation process and are suitable for high-temperature and high-power silicon carbide integrated circuits.

(II) technical scheme

The technical scheme of the invention comprehensively considers the aspects of the characteristics, the process difficulty, the device performance, the cost and the like of the silicon carbide material and provides silicon carbide transverse JFET devices.

The main structure comprises an N + substrate 1, a P + isolation layer 2, a P-layer 3 and a N-drift region 4 which are sequentially arranged above the substrate, wherein two P + gate regions 5 are arranged on the left side above the N-drift region 4, the two P + gate regions 5 are separated by an N-channel region 7, and an N + source contact region 8 is arranged at the top of the N-channel region 7;

N-second drift region 6, located at the right side of the P + gate region, N + drain region 9 located at the top of the right side of the N-second drift region 6, and gate 10, source 11 and drain 12 located above the P + gate region 5, N + source contact region 8 and N + drain contact region 9, respectively.

When the grid of the device is applied with positive bias, the channel is opened, current can flow in from the drain electrode and flow out from the source electrode. The N-channel region 7 is fully occupied by the depletion layer when the gate is negatively biased and the channel is off, while the drain is positively biased to form space charge regions in the N-drift region 4 and the N-second drift region 6.

Preferably, the thickness of the P + isolation layer 2 is 0.2-1 μm, and the doping concentration is 5 × 10¹⁶cm^-3-5×10¹⁷cm^-3(ii) a The thickness of the P-layer 3 is 1-5 μm, and the doping concentration is 1 × 10¹⁵cm^-3-2×10¹⁶cm^-3(ii) a The thickness of the N-drift region 4 is 5-20 μm, and the doping concentration is 2 x 10¹⁴cm^-3-1×10¹⁶cm^-3。

Preferably, the doping concentration of the P + gate region 5 is 5 × 10¹⁸cm^-3Above, the thickness is 0.5 μm-5 μm; the thickness of the N-second drift region 6 is the same as the height of the P + gate region 5, and the doping concentration is the same as that of the N-drift region 4.

Preferably, the N + source contact region 8 and the N + drain contact region 9 are ion implantation regions, the depth of the ion implantation regions is 0.2-0.5 μm, and the nitrogen doping concentration is 2 × 10¹⁸cm^-3-5×10¹⁹cm^-3。

Preferably, the gate electrode 10 forms an ohmic contact with the P + gate region 5The gate material comprises Ti/TaSi₂Pt; the source electrode 11 and the drain electrode 12 are in ohmic contact with the N + source electrode contact region 8 and the N + drain region 9 respectively, and the source electrode is made of TaSi₂/Pt。

In another aspect of the invention, methods of making the lateral silicon carbide JFET device are provided, comprising the steps of:

s1: sequentially growing a P +/P-/N-/P + type epitaxial layer on an N + type silicon carbide substrate;

s2: etching the surface of the silicon carbide to form a gate region;

s3: epitaxially growing an N-type drift layer to fill the groove, and grinding, polishing and flattening the surface;

s4: ion implantation is carried out to form a source contact region and a drain contact region;

s5: and stripping to form the gate, source and drain metals.

Preferably, the S3 includes: and cleaning the epitaxial wafer, carrying out epitaxial growth on N-doped silicon carbide by using HTCVD equipment, completely filling the groove, and then grinding and polishing to remove the N-type epitaxial layer covering the P + gate region 5 to form an N-channel region 7 and an N-second drift region 6.

Preferably, the S5 includes:

s5.1, cleaning the epitaxial wafer, coating glue, photoetching, developing, sputtering metal Ti, and soaking in an acetone solution to strip the metal Ti;

s5.2 coating, photoetching, developing and sputtering TaSi₂Pt, forming Ti/TaSi on the gate region 10 after stripping again₂a/Pt composite metal, TaSi is formed on the N + source contact region 8 and the N + drain contact region 9₂the/Pt composite metal is annealed at 600 ℃ for 30 minutes to form ohmic contact.

(III) advantageous effects

The invention designs silicon carbide transverse JFET devices which are based on commercial N-type silicon carbide substrates, and the high-temperature processes used in the device preparation process are fewer, so that the cost is lower.

Because the silicon carbide transverse JFET device is conductive by virtue of multiple photons and does not have a gate oxide layer which is easy to lose efficacy at high temperature, the electrode contacts of the device are all high-temperature reliable TaSi₂The Pt-based ohmic contact is adopted, so that an integrated circuit formed by the silicon carbide transverse JFET device can work at extremely high temperature, and obvious performance degradation and reliability problems can not occur.

Drawings

Figure 1 is a block diagram of a lateral silicon carbide JFET device of the present invention;

figure 2 is a process flow diagram of a lateral silicon carbide JFET device of the present invention;

FIG. 3 is a schematic diagram of a device manufacturing process step S1 according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a device manufacturing process step S2 according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a device manufacturing process step S3 according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a device manufacturing process step S4 according to an embodiment of the present invention;

the transistor comprises an N + substrate 1, a P + isolation layer 2, a P-layer 3, an N-drift region 4, a P + gate region 5, an N-second drift region 6, an N-channel region 7, an N + source contact region 8, an N + drain region 9, a gate electrode 10, a source electrode 11 and a drain electrode 12.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to specific embodiments and the accompanying drawings.

The aspect of the embodiment of the invention provides lateral silicon carbide JFET devices, the structural schematic diagram of which is shown in fig. 1, the device structure includes N + substrate 1, P + isolation layer 2, P-layer 3 and N-drift region 4, two P + gate regions 5 are arranged on the left side above the N-drift region 4, the two P + gate regions 5 are separated by an N-channel region 7, an N + source contact region 8, N-second drift region 6 is arranged on the top of the N-channel region 7 and on the right side of the P + gate region, N + drain region 9 is arranged on the top of the right side of the N-second drift region 6, and two gates 10, source electrodes 11 and drain electrodes 12 are respectively arranged on the P + gate region 5, the N + source contact region 8 and the N + drain contact region 9.

In the embodiment of the present invention, preferably, the P + isolation layer 2 has a thickness of 0.2 μm to 1 μm, and a doping concentration of 5-10¹⁶cm^-3To 5X 10¹⁷cm^-3(ii) a The thickness of the P-layer 3 is 1-5 μm, and the doping concentration is 1 × 10¹⁵cm^-3To 2X 10¹⁶cm^-3(ii) a The thickness of the N-drift region 4 is 5-20 μm, and the doping concentration is 2 x 10¹⁴cm^-3To 1X 10¹⁶cm^-3。

In the embodiment of the present invention, preferably, the doping concentration of the P + gate region 5 is 5 × 10¹⁸cm^-3Above, 0.5 μm to 5 μm in height; the thickness of the N-second drift region 6 is the same as the height of the P + gate region 5, and the doping concentration is the same as that of the N-drift region 4.

In the embodiment of the present invention, preferably, the N + source contact region 8 and the N + drain contact region 9 are ion implantation regions, each having a depth of 0.2 μm to 0.5 μm and a doping concentration of 2 × 10¹⁸cm^-3To 5X 10¹⁹cm^-3N is used as a doping impurity.

In the embodiment of the present invention, it is preferable that the gate 10 forms an ohmic contact with the P + gate region 5, and the selectable gate material is Ti/TaSi₂Pt; the source electrode 11 and the drain electrode 12 form ohmic contact with the N + source electrode contact region 8 and the N + drain region 9 respectively, and the selectable material is TaSi₂/Pt。

In another aspect of an embodiment of the invention, there is provided a method of making the lateral silicon carbide JFET device, comprising the steps of:

step S1: and sequentially growing a P +/P-/N-/P + type epitaxial layer on the N + -type silicon carbide substrate.

As shown in fig. 3, a P + epitaxial layer 2, a P-epitaxial layer 3, an N-epitaxial layer 4, and a P + epitaxial layer 5 are epitaxially grown in this order on an N + type substrate 1.

Step S2: etching the surface of the silicon carbide to form a gate region;

after cleaning the surface of the epitaxial wafer, silicon dioxide was deposited to a thickness of 3 μm on the surface of the silicon carbide wafer, as shown in fig. 4. And after coating, photoetching, developing and hardening, etching the silicon dioxide by taking the photoresist as a mask. And etching the silicon carbide material to the surface of the N-layer by taking the etched silicon dioxide as a mask to form a P + gate region 5.

Step S3: epitaxially growing an N-type drift layer again to fill the groove, and then performing surface grinding and polishing and flattening;

as shown in fig. 5, the epitaxial wafer is cleaned again, N-doped silicon carbide is epitaxially grown by using HTCVD equipment, after the trenches are completely filled with the epitaxially grown silicon carbide, the N-type epitaxial layer covering the P + gate region 5 is removed by polishing, so that the surface of the wafer is planarized, and an N-channel region 7 and an N-second drift region 6 are formed.

S4: ion implantation is carried out to form a source contact region and a drain contact region;

as shown in fig. 6, after the epitaxial wafer was cleaned, silicon dioxide was deposited on the surface of the silicon carbide to a thickness of 2 μm, and the silicon dioxide was etched using the photoresist as a mask. And (3) taking the etched silicon dioxide as a mask, implanting nitrogen into ions, sputtering a carbon film, and then activating and annealing at 1800 ℃ for 2 hours. The carbon film is etched away to form an N + source contact region 8 and an N + drain contact region 9.

S5: and stripping to form the gate, source and drain metals.

As shown in fig. 1, the wafer is cleaned again, coated with glue, photoetched and developed, then sputtered with metal Ti, and immersed in acetone solution to strip the metal Ti. Then coating glue, photoetching and developing again, sputtering TaSi2/Pt, stripping again and forming Ti/TaSi on the gate region 10₂a/Pt composite metal, TaSi is formed on the N + source contact region 8 and the N + drain contact region 9₂the/Pt composite metal is annealed at 600 ℃ for 30 minutes to form ohmic contact.

The above embodiments, objects, technical solutions and advantages of the present invention have been described in further , it should be understood that the above embodiments are only examples of the present invention and are not intended to limit the present invention.