TECHNICAL FIELD

One embodiment of the present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. Alternatively, one embodiment of the present invention relates to a semiconductor wafer, a module, and an electronic device.

In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A semiconductor element such as a transistor, a semiconductor circuit, an arithmetic device, and a memory device are each an embodiment of a semiconductor device. In some cases, it can be said that a display device (e.g., a liquid crystal display device and a light-emitting display device), a projection device, a lighting device, an electro-optical device, a power storage device, a memory device, a semiconductor circuit, an imaging device, an electronic device, and the like include a semiconductor device.

Note that one embodiment of the present invention is not limited to the above technical field. One embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter.

BACKGROUND ART

As semiconductor thin films applicable to the transistors, silicon-based semiconductor materials have been widely known, but oxide semiconductors have been attracting attention as alternative materials. Examples of oxide semiconductors include not only single-component metal oxides, such as indium oxide and zinc oxide, but also multi-component metal oxides. Among the multi-component metal oxides, in particular, an In—Ga—Zn oxide (hereinafter also referred to as IGZO) has been actively studied.

From the studies on IGZO, in an oxide semiconductor, a CAAC (c-axis aligned crystalline) structure and an nc (nanocrystalline) structure, which are not single crystal nor amorphous, have been found (see Non-Patent Documents 1 to 3). In Non-Patent Documents 1 and 2, a technique for fabricating a transistor using an oxide semiconductor having the CAAC structure is disclosed. Moreover, Non-Patent Documents 4 and 5 disclose that a fine crystal is included even in an oxide semiconductor which has lower crystallinity than an oxide semiconductor having the CAAC structure or the nc structure.

In addition, a transistor which includes IGZO as an active layer has an extremely low off-state current (see Non-Patent Document 6), and an LSI and a display utilizing the transistor characteristics have been reported (see Non-Patent Documents 7 and 8).

REFERENCE

Non-Patent Document

[Non-Patent Document 1] S. Yamazaki et al., “SID Symposium Digest of Technical Papers”, 2012, volume 43, issue 1, p. 183-186[Non-Patent Document 2] S. Yamazaki et al., “Japanese Journal of Applied Physics”, 2014, volume 53, Number 4S, p. 04ED18-1-04ED18-10[Non-Patent Document 3] S. Ito et al., “The Proceedings of AM-FPD'13 Digest of Technical Papers”, 2013, p. 151-154[Non-Patent Document 4] S. Yamazaki et al., “ECS Journal of Solid State Science and Technology”, 2014, volume 3, issue 9, p. Q3012-Q3022[Non-Patent Document 5] S. Yamazaki, “ECS Transactions”, 2014, volume 64, issue 10, p. 155-164[Non-Patent Document 6] K. Kato et al., “Japanese Journal of Applied Physics”, 2012, volume 51, p. 021201-1-021201-7[Non-Patent Document 7] S. Matsuda et al., “2015 Symposium on VLSI Technology Digest of Technical Papers”, 2015, p. T216-T217[Non-Patent Document 8] S. Amano et al., “SID Symposium Digest of Technical Papers”, 2010, volume 41, issue 1, p. 626-629

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An object of one embodiment of the present invention is to provide a highly reliable semiconductor device. Another object of one embodiment of the present invention is to provide a semiconductor device having favorable electrical characteristics. Another object of one embodiment of the present invention is to provide a semiconductor device with high on-state current. Another object of one embodiment of the present invention is to provide a semiconductor device having high frequency characteristics. Another object of one embodiment of the present invention is to provide a semiconductor device that can be miniaturized or highly integrated. Another object of one embodiment of the present invention is to provide a semiconductor device with high productivity.

An object of one embodiment of the present invention is to provide a semiconductor device capable of retaining data for a long time. Another object of one embodiment of the present invention is to provide a semiconductor device capable of high-speed data writing. Another object of one embodiment of the present invention is to provide a semiconductor device with high design flexibility. Another object of one embodiment of the present invention is to provide a semiconductor device with low power consumption. Another object of one embodiment of the present invention is to provide a novel semiconductor device.

Note that the description of these objects does not preclude the existence of other objects. One embodiment of the present invention does not have to achieve all these objects. Other objects are apparent from and can be derived from the description of the specification, the drawings, the claims, and the like.

Means for Solving the Problems

One embodiment of the present invention is a semiconductor device which includes a first oxide, a second oxide, a first conductor, a second conductor, a third conductor, a first insulator, and a second insulator. The first conductor is provided in contact with a top surface of the first oxide. The second conductor is provided in contact with the top surface of the first oxide. The first insulator is provided over the first conductor and the second conductor. The second oxide is provided in contact with the top surface of the first oxide. The second insulator is provided over the second oxide. The third conductor is provided over the second insulator. The first insulator has a function of inhibiting diffusion of oxygen. The first oxide includes indium, an element M (M is gallium, yttrium, or tin), and zinc. The first oxide includes a first region overlapping with the third conductor. A region of the first region in contact with the second oxide includes a region in which an atomic ratio of aluminum to the element M is less than 0.1.

One embodiment of the present invention is a semiconductor device which includes a first oxide, a second oxide, a first conductor, a second conductor, a third conductor, a first insulator, and a second insulator. The first conductor is provided in contact with a top surface of the first oxide. The second conductor is provided in contact with the top surface of the first oxide. The first insulator is provided over the first conductor and the second conductor. The second oxide is in contact with the top surface of the first oxide. The second insulator is provided over the second oxide. The third conductor is provided over the second insulator. The first insulator includes aluminum. The first oxide includes indium, an element M (M is gallium, yttrium, or tin), and zinc. The first oxide includes a first region overlapping with the third conductor. A region of the first region in contact with the second oxide includes a region in which an atomic ratio of aluminum to the element M is less than 0.1.

One embodiment of the present invention is a semiconductor device which includes a first oxide, a second oxide, a third oxide, a first conductor, a second conductor, a third conductor, a fourth conductor, a first insulator, a second insulator, a third insulator, a fourth insulator, and a fifth insulator. The fifth insulator is provided over the fourth conductor. The third insulator is provided over the fifth insulator. The third oxide is provided over the third insulator. The first oxide is provided over the third oxide. The first conductor is provided in contact with a top surface of the first oxide. The second conductor is provided in contact with the top surface of the first oxide. The first insulator is provided over the first conductor and the second conductor. The fourth insulator is provided over the first insulator. An opening reaching the first oxide is provided in the first insulator and the fourth insulator. The second oxide is provided in contact with the top surface of the first oxide to cover an inner wall of the opening. The second insulator is provided to cover the inner wall of the opening with the second oxide therebetween. The third conductor is provided to be embedded in the opening with the second insulator and the second oxide therebetween. The first insulator includes aluminum. The first oxide includes indium, an element M (M is gallium, yttrium, or tin), and zinc. The first oxide includes a first region overlapping with the third conductor. A region of the first region in contact with the second oxide includes a region in which an atomic ratio of aluminum to the element M is less than 0.1. The fourth conductor includes a region overlapping with the third conductor with the first region therebetween.

In the semiconductor device described above, it is preferable that the second oxide include indium, the element M (M is gallium, yttrium, or tin), and zinc and the first region include a channel formation region. In a cross section in a channel width direction, a region of the first region in contact with the second oxide preferably includes a region including a c-axis aligned crystal along a normal direction to a bottom surface of the first oxide, and a region of the second oxide in contact with the first region preferably includes a region including a c-axis aligned crystal along the normal direction to the bottom surface of the first oxide.

In the semiconductor device described above, it is preferable that the first oxide include a second region in contact with the first conductor and a third region in contact with the second conductor. A thickness of the first oxide in the first region is preferably smaller than a thickness of the first oxide in the second region. A thickness of the first oxide in the first region is preferably smaller than a thickness of the first oxide in the third region.

One embodiment of the present invention is a fabrication method of a semiconductor device including a first oxide, a second oxide, a third oxide, a first conductor, a second conductor, a third conductor, a first insulator, a second insulator, a third insulator, and a fourth insulator. The following are performed: forming the third insulator; forming the third oxide over the third insulator; forming the first oxide over the third oxide using a target including indium, an element M (M is gallium, yttrium, or tin), and zinc by a sputtering method; forming a conductive film to be the first conductor and the second conductor over the first oxide; processing the third oxide, the first oxide, and the conductive film into an island shape; forming the first insulator so as to include aluminum over the third insulator and the conductive film; forming the fourth insulator over the first insulator; forming an opening from which the first oxide is exposed in the fourth insulator, the first insulator, and the conductive film, so that the first conductor and the second conductor are formed; removing part of the exposed first oxide; forming the second oxide over part of the first oxide and the fourth insulator; forming the second insulator over the second oxide; forming the third conductor over the second insulator; and removing part of the second oxide, the second insulator, and the third conductor to expose part of the fourth insulator.

In the fabrication method of the semiconductor device described above, a removal of part of the first region is performed by using diluted ammonia water.

In the fabrication method of the semiconductor device described above, an ammonia concentration of the diluted ammonia water is greater than or equal to 0.1% and less than or equal to 0.5%.

In the fabrication method of the semiconductor device described above, a region of the first oxide in contact with the second oxide includes a region in which an atomic ratio of aluminum to the element M is less than 0.1.

Effect of the Invention

According to one embodiment of the present invention, it is possible to provide a highly reliable semiconductor device. According to another embodiment of the present invention, a semiconductor device having favorable electrical characteristics can be provided. According to another embodiment of the present invention, a semiconductor device with high on-state current can be provided. According to another embodiment of the present invention, a semiconductor device having high frequency characteristics can be provided. According to another embodiment of the present invention, a semiconductor device that can be miniaturized or highly integrated can be provided. According to another embodiment of the present invention, a semiconductor device with high productivity can be provided.

A semiconductor device capable of retaining data for a long time can be provided. A semiconductor device with high-speed data writing can be provided. A semiconductor device with high design flexibility can be provided. Alternatively, a semiconductor device with low power consumption can be provided. A novel semiconductor device can be provided.

Note that the descriptions of the effects do not disturb the existence of other effects. One embodiment of the present invention does not have to have all of these effects. Effects other than these will be apparent from the description of the specification, the drawings, the claims, and the like and effects other than these can be derived from the description of the specification, the drawings, the claims, and the like.

