CMP 垫和凹槽的 3D 计量

2023-07-03 18:07

3D metrology of CMP pads and grooves

CMP垫和凹槽的3D计量

What are CMP pads and why measure them?

什么是CMP垫以及为什么要测量它们?

CMP pads are consumables
used in the
CMP (chemical mechanical polishing or planarization) process
employed in the semi-conductor industry to flatten and polish silicon wafers. The pads are disk shaped, most commonly made from hard and porous polyurethane foam, and patterned with narrow high-aspect-ratio grooves (see image).

CMP垫是用于半导体行业CMP(化学机械抛光或平面化)工艺的耗材,用于平整和抛光硅晶圆。垫子是圆盘形的,最常见的是由坚硬多孔聚氨酯泡沫制成,并带有狭窄的高纵横比凹槽图案(见图)。

The
function of the CMP process
is to improve the performance of silicon wafers, which in turn are used in the development of high-performance microprocessor and memory chips. Since wafers are built up in several layers, each wafer typically undergoes the CMP process several times.

CMP工艺的作用是提高硅片的性能,进而用于开发高性能微处理器和存储芯片。由于晶圆由多层构成,因此每个晶圆通常要经过多次CMP工艺。

High-precision 3D metrology of CMP pads is required
both in the pad manufacture and during the CMP process to ensure maximum process efficiency and efficacy.

在垫制造和CMP过程中都需要对CMP垫进行高精度3D计量,以确保最大的工艺效率和功效。

CMP pad measurement example – close-up of a 10x10mm square of CMP pad surface, and 3D point cloud data obtained with Novacam SurfaceInspect reveals the depth and shape of the narrow channels down to the micron.

CMP垫测量示例 - 10x10 平方毫米CMP垫表面的特写,以及使用 Novacam SurfaceInspect 获得的3D点云数据揭示了细至微米的狭窄通道的深度和形状。

How does the CMP process work?

CMP流程如何运作?

In the CMP process:

在CMP过程中:

The
silicon wafer
is mounted on a rotating
wafer carrier
and pressed against a
CMP pad
affixed on a rotating
platen.

硅晶片安装在旋转的晶片载体上,并压在旋转台板上的CMP垫上。

At the same time, ultra-fine chemical
polishing slurry
is sprayed onto and channeled around the pad surface. Slurry distribution is done via tiny narrow
grooves
machined in specific patterns on the CMP pad surface.

同时,将超细化学抛光浆喷到垫表面并在其周围形成通道。浆料分布是通过在CMP垫表面上以特定图案加工的微小窄槽完成的。

The corrosiveness of the slurry together with the asperities on the CMP pad surface wear away the wafer surface until the desired flatness and polish are achieved.

研磨液的腐蚀性与 CMP 垫表面的粗糙度一起磨损晶圆表面,直到达到所需的平整度和抛光度。

To extend the lifespan of the CMP pad, the pad is typically reconditioned on a continuous or intermittent basis.
This is done using a
pad conditioner, which slices and pops open newly uncovered bubbles in the pad with diamond tips on its surface.

为了延长CMP垫的使用寿命,通常会连续或间歇地修复垫。这是使用垫调节器完成的,该调节器将垫中新发现的气泡切成薄片并弹出,其表面带有金刚石尖端。

Simplified diagram of CMP (Chemical Mechanical Planarization/Polishing) process

CMP(化学机械平面化/抛光)工艺简图

Why is quality control of CMP pads crucial?

为何CMP垫的质量控制至关重要?

First, both the silicon wafer and the CMP pads are costly items.

首先,硅片和CMP垫都是昂贵的物品。

Second, the geometry and condition of CMP pad surfaces greatly affects CMP process efficacy.

其次,CMP垫表面的几何形状和条件极大地影响CMP工艺效果

For example, the
grooves on CMP pads
must be measured because the pattern, depth, and shape of these tiny channels influence slurry consumption and distribution, material removal rate (MRR), the rate of accumulation of polishing debris, as well as potential creation of scratches on wafers by this debris.

例如,必须测量CMP垫上的凹槽,因为这些微小通道的图案、深度和形状会影响研磨液的消耗和分布、材料去除率 (MRR)、抛光碎屑的积累速率以及潜在的抛光这些碎屑在晶圆上造成划痕。

Zoom-in view of one of a CMP pad groove with tool marks on the groove bottom readily visible. Measurements are in mm.

放大CMP 垫凹槽的一个视图,凹槽底部的工具标记清晰可见。测量单位为毫米。

3D measurements for CMP pad manufacture and CMP process in general

一般CMP垫制造和CMP工艺的3D测量

Novacam 3D metrology systems are uniquely suitable to carry out fast, high-precision 3D metrology of:

Novacam 3D测量系统特别适合执行快速、高精度的3D量:

CMP pads, including the hard-to-measure grooves and lands (the surface between the grooves)

CMP垫,包括难以测量的凹槽和平台(凹槽之间的表面)

CMP pad conditioners

CMP垫调节器

Wafers, including their flatness.

晶圆,包括平整度。

Novacam systems’ capabilities include:

Novacam 系统的功能包括:

Non-contact 3D surface measurements with 1 μm (40 μin.) axial resolution

具有 1 μm(40 μin.)轴向分辨率的非接触式3D表面测量

Ability to scan high-aspect-ratio features such as the narrow CMP pad grooves

能够扫描高纵横比特征,例如狭窄的CMP垫槽

High-speed surface acquisition – up to 100,000 3D measurements/sec

高速表面采集——高达10万次3D测量/

Dimensional and roughness measurements with the same probe

使用同一探头进行尺寸和粗糙度测量

Ability to obtain long profiles

能够获得较长的配置文件

Facility for automated measurement both in lab and in high-volume automated production.

在实验室和大批量自动化生产中进行自动化测量的设施。

View from below of the CMP pad grooves clearly shows the tool marks of the bit used to machine the channels. Perfect cylinders were fitted on each groove to obtain a mean radius measurement. Here, the measured radii of curvature were found to vary between 475 and 528 μm

CMP垫槽下方的视图清楚地显示了用于加工通道的钻头的工具标记。完美的圆柱体安装在每个凹槽上以获得平均半径测量值。在这里,测得的曲率半径在475~ 528 μm之间变化


文件:AN-THICKNESS-1.22021-06-03

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