Super junction device with multiple embedded P islands and N channels and preparation method thereof

[0044] Example one

[0045] The present invention provides a method for preparing an N-channel super junction device with multiple P islands embedded therein. The preparation method includes the following steps:

[0046] In step 1), a semiconductor substrate 21 is provided, and a layer of N-type drift region 22 is prepared on the semiconductor substrate 21 by N-type ion implantation; specifically, the semiconductor substrate 21 is a bulk silicon substrate or SOI substrate. See figure 2 As shown in the figure, in this embodiment, taking the semiconductor substrate 21 as an SOI substrate as an example for description, the N-type drift region 22 is formed in the top silicon of the SOI substrate, specifically, The top silicon of the SOI substrate is doped with N-type ions of group V elements (such as phosphorus, arsenic, antimony, etc.) to replace the positions of silicon atoms in the crystal lattice to form an N-type drift region 22.

[0047] Then, a mask 3 is provided with a plurality of sets of ion implantation windows 31 arranged in parallel. The plurality of sets of ion implantation windows 31 gradually decrease from one side of the mask 3 to the other side, and the mask 3 One side of 3 tends to increase the shielding part on the other side. See image 3 , Shows a schematic diagram of the structure of the mask used in the preparation method of the present invention.

[0048] In step 2), boron ions are injected into the N-type drift region 22 and the concentration distribution of boron ions is controlled by the mask 3; please refer to Figure 4 , That is, through a mask in which one side of the ion implantation window 31 is gradually reduced toward the other side, and the shielding part is sequentially increased, the boron ion implantation used to form the multi-P island structure in the N-type drift region 22 is performed to achieve The purpose of controlling the concentration distribution of boron ions.

[0049] In step 3), the semiconductor substrate 21 implanted with boron ions in step 2) is annealed to form a plurality of island-shaped P regions 23 spaced apart and arranged in parallel in the N-type drift region 22, and each island The P-shaped area 23 decreases linearly from one end to the other end, see Figure 5.

[0050] In step 4), a P-type body region 24 is prepared on the N-type drift region 22 and adjacent to the big end of the island-shaped P region 23, and an N-type source is prepared above the P-type body region 24 A region 25, a P-type body contact region 26, and a gate oxide layer 27; an N-type drain region 28 is formed on the N-type drift region 22 and adjacent to the small head end of the island-shaped P region 23. See Image 6 The island-shaped P region 23 is a P island structure from large to small in the direction from the N-type source region 25 to the N-type drain region 28. The large end of the P island structure is adjacent to the P-type body region 24. The small head end of the island structure is adjacent to the N-type drain region 28. Since any direction around the embedded island-shaped P region 23 is N-type, there is depletion between the two, and due to the substrate auxiliary consumption under high pressure The depletion effect increases from the source end to the drain end in turn, so the island-shaped P region 23 correspondingly changes from large to small in the direction from the source end to the drain end, so as to complement the substrate-assisted depletion effect and finally achieve charge balance. .

[0051] Example two

[0052] This embodiment is the same as step 1) and step 4) in the first embodiment above, so it will not be repeated. In step 2 in this embodiment, boron ions are injected into the N-type drift region 22 repeatedly and borrowed. The concentration distribution of boron ions is controlled by the mask 3, and annealed in step 3), so that a plurality of mutually spaced and horizontally parallel arrangements and longitudinally parallel arrangements can be formed in the N-type drift region 22 The island-shaped P zone 23, which looks like Figure 7 Shown.

[0053] Example three

[0054] The invention also provides an N-channel super junction device with embedded multiple P islands, please refer to Image 6 , Showing a schematic diagram of the structure of an N-channel super junction device with multiple P islands embedded in the present invention. As shown in the figure, the N-channel super junction device with multiple P islands embedded includes: a semiconductor substrate 21 formed on the semiconductor substrate The N-type drift region 22 on the bottom 21, the P-type body region 24 on one side of the N-type drift region 22, and the N-type drain region 28 on the other side of the N-type drift region 22, the P The type body 24 includes an N type source region 25, a P type body contact region 27 and a gate oxide layer 27.

[0055] A plurality of island-shaped P regions 23 spaced apart and arranged in parallel are formed in the N-type drift region 22, and each island-shaped P region 23 linearly decreases from the N-type source region 25 to the N-type drain region 28. The semiconductor substrate 21 is a bulk silicon substrate or an SOI substrate.

[0056] In a specific manufacturing process, the N-type drift region 22 is formed by implanting boron ions and controlling the concentration distribution of boron ions by shielding the mask with a preset pattern. See Figure 4 The mask plate 3 of the preset pattern is provided with multiple sets of ion implantation windows 31 arranged in parallel, and the multiple sets of ion implantation windows 31 decrease sequentially from one side of the mask plate 3 to the other side, and The shielding part of the mask 3 on one side tends to increase gradually toward the other side. That is, during the process of implanting boron ions, one side of the ion implantation window 31 is gradually reduced toward the other side, and the shielding portion is sequentially increased to form multiple P islands in the P-type drift region 22. The structure of boron ion implantation can achieve the purpose of controlling the concentration distribution of boron ions.

[0057] In this embodiment, temporarily taking the semiconductor substrate 21 as an SOI substrate as an example, the N-type drift region 22 is formed in the top silicon of the SOI substrate, specifically, on the SOI substrate The top silicon is doped with group V elements (such as phosphorus, arsenic, antimony, etc.) to replace silicon atoms in the crystal lattice to form an N-type drift region 22. The N-type drift region 22 and the island-shaped P region 23 are formed in the top silicon of the SOI substrate. The island-shaped P region 23 is a P island structure that changes from larger to smaller in the direction from the N-type source region 25 to the N-type drain region 28. The large end of the P island structure is adjacent to the P-type body region 24, and the P island The small head end of the structure is adjacent to the N-type drain region 28. Since any direction around the embedded island-shaped P region 23 is N-type, there is depletion between the two, and because the substrate is assisted by the depletion under high pressure The effect increases from the source end to the drain end in order, so the island-shaped P region 23 correspondingly changes from larger to smaller in the direction from the source end to the drain end, so as to complement the substrate-assisted depletion effect and finally achieve charge balance.

[0058] In another embodiment, the plurality of island-shaped P regions 23 formed in the N-type drift region 22 are spaced apart from each other and arranged in parallel in the horizontal direction and arranged in parallel in the vertical direction.

[0059] In summary, the N-channel super junction device with multiple P islands embedded in the present invention and the preparation method thereof are to directly form a plurality of embedded island-shaped P regions in the N-type drift region by ion implantation. Any direction around the embedded island-shaped P region is N-type, and depletion occurs between the two. Because the substrate-assisted depletion effect under high pressure increases from source to drain, the island-shaped P region corresponds to The ground changes from large to small in the direction from the source end to the drain end, so as to complement the substrate-assisted depletion effect and finally achieve charge balance, thereby solving the problem of uneven electric field distribution in the drift region in the prior art. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial value.