Preparation method of phase change memory and phase change memory

Abstract

A preparation method of a phase change memory and the phase change memory, comprising the following steps: providing a base, the base comprising a substrate (200), a bottom electrode (201), a nitride layer (203), a heater (207), the heater (207) being located in the nitride layer (203), and fin-shaped sacrificial layers (206) on both sides of the heater (207), the fin-shaped sacrificial layers (206) being selectively etched; selectively etching the fin-shaped sacrificial layers (206) to form fin-shaped grooves on both sides of the heater (207); depositing an oxide layer (208) at the fin-shaped grooves to form an air gap (208a) surrounding the heater; and depositing a patterned phase change material layer (209) and a top electrode (210). Since the air gap (208a) has better thermal insulation performance than the nitride layer or the oxide layer, the heater (207) is surrounded by the air gap (208a), the lateral heat dissipation is reduced, the thermal efficiency is higher, and the performance of the phase change memory is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a preparation method of a phase change memory and the phase change memory. Background Art

[0002] In existing technology, 1T-1R mushroom-shaped phase-change memory is a common low-density memory. The smaller the size of the phase-change memory heater, the higher the thermal efficiency. Therefore, the industry generally adopts the method of reducing the heater size to improve thermal efficiency. However, if a small heater of 15-25μm is produced, it is beyond the feasible range of the current industry back-end process. Therefore, the thermal efficiency of the heater with current technology is limited. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a preparation method of a phase change memory and a phase change memory, so as to solve the problem of low thermal efficiency of the phase change memory.

[0004] In order to solve the above problems, the present invention provides a method for preparing a phase change memory, comprising the following steps: providing a base, the base comprising a substrate, a bottom electrode, a nitride layer, a heater, the heater being located in the nitride layer, and fin-shaped sacrificial layers on both sides of the heater, the fin-shaped sacrificial layers being selectively etched; selectively etching the fin-shaped sacrificial layers to form fin-shaped grooves on both sides of the heater; depositing an oxide layer at the fin grooves to form an air gap surrounding the heater; and depositing a patterned phase change material layer and a top electrode.

[0005] The present invention also provides a phase change memory, which includes: a substrate; a bottom electrode, which is located on the substrate; a nitride layer, which covers the substrate and the bottom electrode; a heater, which is located in the nitride layer and connected to the bottom electrode; an air gap and an oxide layer that wraps the heater, which are located in the nitride layer; a phase change material layer, which is located above the nitride layer and connected to the heater; and a top electrode, which is located above the phase change material layer.

[0006] Since the air gap has better thermal insulation performance than the nitride layer or the oxide layer, the heater is surrounded by the air gap, the lateral heat energy dissipation is reduced, the thermal efficiency is higher, and the performance of the phase change memory is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Attachment Figure 1 Shown is a schematic diagram of the steps described in a specific embodiment of the present invention.

[0008] Attachment Figures 2A-2D The attached Figure 1 Schematic diagram of the process of steps S10-S13.

[0009] Attachment Figure 3 The following is a diagram showing a specific embodiment of the present invention. Figure 2A Schematic diagram of the steps of the structure shown.

[0010] Attachment Figures 4A-4J The attached Figure 3 Process diagram of steps S300-S309. DETAILED DESCRIPTION

[0011] The following describes in detail a specific embodiment of a method for preparing a phase change memory provided by the present invention in conjunction with the accompanying drawings.

[0012] Attachment Figure 1 The figure shows a schematic diagram of the steps of a specific embodiment of the present invention, including:

[0013] Step S10, providing a substrate, providing a substrate, the substrate including a substrate, a bottom electrode, a nitride layer, a heater, the heater being located in the nitride layer, and fin-shaped sacrificial layers on both sides of the heater, the fin-shaped sacrificial layers being selectively etched; step S11, selectively etching the fin-shaped sacrificial layers to form fin-shaped grooves on both sides of the heater; step S12, depositing an oxide layer at the fin grooves and forming an air gap surrounding the heater; step S13, depositing a patterned phase change material layer and a top electrode.

[0014] Attachment Figure 2A As shown, referring to step S10, a base is provided, which includes a substrate 200, a bottom electrode 201, a nitride layer 203, a heater 207, the heater 207 is located in the nitride layer 203, and the sidewall nitride layer 203 and the fin-shaped sacrificial layer 206 on both sides of the heater 207, and the fin-shaped sacrificial layer 206 can be selectively etched.

[0015] In a specific embodiment of the present invention, the above structure can be formed by the following method, and refer to the attached Figure 33. Schematic diagram of the implementation of the following steps: Step 300, providing a substrate, wherein the surface of the substrate has a bottom electrode 201; Step 301, forming a fin-shaped oxide on the surface of the bottom electrode; Step 302, forming a first nitride layer around the fin-shaped oxide; Step 303, continuing to form a patterned oxide layer and a second nitride layer on the surface of the first nitride layer, wherein the fin-shaped oxide is exposed in the hollow of the patterned oxide layer and the second nitride layer; Step 304, selectively etching the fin oxide to form a fin-shaped groove; Step 305, depositing a sacrificial layer in the fin-shaped groove to fill the groove to form a fin-shaped sacrificial layer; Step 306, forming a keyhole in the middle of the fin-shaped sacrificial layer, wherein the keyhole exposes the bottom electrode; Step 307, thinning to the oxide layer; Step 308, depositing a heater at the keyhole; Step 309, thinning to the first nitride layer to form a structure including a bottom electrode, a nitride layer covering the bottom electrode, a heater on the nitride layer, and a fin-shaped sacrificial layer on both sides of the heater.

[0016] Attachment Figure 4A As shown, referring to step 300, a substrate 200 is provided, and a bottom electrode 201 is formed on the surface of the substrate 200. In one embodiment of the present invention, the substrate 200 is made of silicon, and the bottom electrode 201 is made of metal. In other embodiments, the substrate 200 may be made of sapphire, silicon carbide, gallium nitride, or other common substrate materials in the semiconductor field.

[0017] Attachment Figure 4B As shown, referring to step 301, a fin-shaped oxide 202 is formed on the surface of the bottom electrode 201. The fin-shaped oxide 202 is formed by depositing an oxide layer, patterning and etching, and finally forming a symmetrical structure arranged in a fish-fin shape.

[0018] Attachment Figure 4C As shown, referring to step 302, a first nitride layer 203 is formed around the fin oxide 202. The first nitride layer 203 has the same thickness as the fin oxide 202.

[0019] Attachment Figure 4D As shown, referring to step 303, a patterned oxide layer 204 and a second nitride layer 205 are formed on the surface of the first nitride layer 203, and the fin oxide 202 is exposed in the hollows of the patterned oxide layer 204 and the second nitride layer 205. In a specific embodiment, the above structure is deposited on the surface of the first nitride layer 203 by physical vapor deposition or chemical vapor deposition. Figure 4C An oxide layer and a nitride layer are deposited on the surface of the structure shown, and patterning and etching are performed to remove the structure above the fin oxide 202.

[0020] Attachment Figure 4E As shown, referring to step 304, the fin oxide 202 is selectively etched to form a fin groove. In one embodiment of the present invention, hydrofluoric acid is used as an etchant in the selective etching process.

[0021] Attachment Figure 4F As shown, referring to step 305, a sacrificial layer is deposited in the fin-shaped groove to fill the groove, forming a fin-shaped sacrificial layer 206. In a specific embodiment, the fin-shaped sacrificial layer 206 is made of polysilicon material.

[0022] Attachment Figure 4G As shown, referring to step 306 , a keyhole is formed in the middle of the fin-shaped sacrificial layer 206 , wherein the keyhole exposes the bottom electrode 201 , and sidewall nitride layers 203 are left on both sides of the keyhole.

[0023] Attachment Figure 4H As shown, referring to step 307, the thinning is performed to the oxide layer 204. In a specific embodiment, the thinning method adopts chemical mechanical polishing.

[0024] Attachment Figure 4I As shown, referring to step 308, a heater 207 is deposited at the keyhole. In a specific embodiment, the heater 207 is made of TiN or TaN material; and the deposition method is physical vapor deposition or chemical vapor deposition.

[0025] Attachment Figure 4J As shown, referring to step 309, the first nitride layer 203 is thinned to form a base including a substrate 200, a bottom electrode 201, a nitride layer 203, a heater 207 on the nitride layer 203, and sidewall nitride layers 203 on both sides of the heater 207 and a fin-shaped sacrificial layer 206. In a specific embodiment, the thinning method uses chemical mechanical polishing.

[0026] After the above steps are completed, the attached Figure 2A Based on the structure shown in FIG, the following steps are continued.

[0027] Attachment Figure 2B As shown, in step S11 , the fin-shaped sacrificial layer 206 is selectively etched to form fin-shaped grooves on both sides of the heater 207 , and the heater 207 has sidewall nitride layers 203 on both sides.

[0028] Attachment Figure 2CAs shown, referring to step S12, an oxide layer 208 is deposited in the fin-shaped recess to form an air gap 208a surrounding the heater 207. In one specific embodiment, the deposition method uses physical vapor deposition or chemical vapor deposition. Due to the limited filling capacity of such deposition methods, the air gap 208a surrounding the heater 207 is generated during the deposition process. In another specific embodiment, the oxide layer 208 that exceeds the height of the first nitride layer 203 is chemically mechanically polished until it is flush with the first nitride layer 203.

[0029] Attachment Figure 2D As shown, referring to step S13, a patterned phase change material layer 209 and a top electrode 210 are deposited. The phase change material layer 209 is made of GST material.

[0030] Attachment Figure 2D The figure shows a schematic structural diagram of a specific embodiment of a phase change memory obtained after the above steps are implemented, including: a substrate 200; a bottom electrode 201, the bottom electrode 201 is located on the substrate 200; a nitride layer 203, the nitride layer 203 covering the substrate 200 and the bottom electrode 201; a heater 207, the heater 207 is located in the nitride 203 layer and connected to the bottom electrode 201, the heater 207 is made of TiN or TaN material; an air gap 208a and an oxide layer 208 surrounding the heater 207, the air gap 208a and the oxide layer 208 are located in the nitride layer 203; a phase change material layer 209, the phase change material layer 209 is located above the nitride layer 203 and connected to the heater 207, the phase change material layer is made of GST material; and a top electrode 210, the top electrode 210 is located above the phase change material layer 209.

[0031] The above description is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a phase change memory, characterized in that: The steps include: Providing a substrate, the substrate comprising a substrate, a bottom electrode, a first nitride layer, a heater, the heater being located in the first nitride layer, and sidewall nitride layers and a fin-shaped sacrificial layer on both sides of the heater, wherein the fin-shaped sacrificial layer can be selectively etched; Selectively etching the fin-shaped sacrificial layer to form fin-shaped grooves on both sides of the heater, with the sidewall nitride layer on both sides of the heater; depositing an oxide layer at the fin-shaped groove and forming an air gap surrounding the heater, wherein the air gap and the oxide layer are located between the sidewall nitride layer and the first nitride layer; depositing a patterned phase change material layer and a top electrode; The formation of the substrate is further: Providing the substrate, wherein the bottom electrode is provided on the surface of the substrate; forming a fin-shaped oxide on a surface of the bottom electrode; forming the first nitride layer around the fin oxide; Continue to form a patterned oxide layer and a second nitride layer on the surface of the first nitride layer, wherein the fin oxide is exposed in the hollows of the patterned oxide layer and the second nitride layer; Selectively etching the fin-shaped oxide to form the fin-shaped groove; Depositing a sacrificial layer in the fin-shaped groove to fill the groove, thereby forming the fin-shaped sacrificial layer; forming a keyhole in the middle of the fin-shaped sacrificial layer, wherein the keyhole exposes the bottom electrode, and the sidewall nitride layer is left on both sides of the keyhole; thinning to the oxide layer; depositing the heater at the keyhole; The thickness is reduced to the first nitride layer.

2. The method according to claim 1, wherein The selective etching of the fin oxide layer uses hydrofluoric acid as an etchant.

3. The method according to claim 1, wherein The fin-shaped sacrificial layer is made of polysilicon material.

4. The method according to claim 1, wherein The heater is made of TiN or TaN material.

5. The method according to claim 1, wherein The deposition method adopts physical vapor deposition or chemical vapor deposition, and the air gap surrounding the heater is generated during the deposition process.

6. The method according to claim 1, wherein The phase change material layer is made of GST material.

7. A phase change memory, characterized in that: The phase change memory is obtained by the preparation method according to claim 1, and the phase change memory comprises: a substrate; a bottom electrode, the bottom electrode being located on the substrate; a first nitride layer covering the substrate and the bottom electrode; a heater, the heater being located in the first nitride layer and connected to the bottom electrode, and having sidewall nitride layers on both sides of the heater; an air gap and an oxide layer surrounding the heater, wherein the air gap and the oxide layer are located between the sidewall nitride layer and the first nitride layer; a phase change material layer, the phase change material layer being located above the first nitride layer and connected to the heater; and A top electrode is located above the phase change material layer.

8. The phase change memory according to claim 7, wherein: The heater is made of TiN or TaN material.

9. The phase change memory according to claim 7, wherein: The phase change material layer is made of GST material.

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