酸性条件下YAG晶体化学机械抛光去除机理研究

胡江川; 黄颖; 赵方; 孙锐; 刘杰; 杨佳; 卢忠文; 迭俊珲; 黄金勇

doi:10.11884/HPLPB202638.260021

酸性条件下YAG晶体化学机械抛光去除机理研究

doi: 10.11884/HPLPB202638.260021

中国工程物理研究院激光聚变研究中心，四川绵阳 621900

基金项目: 国家自然科学基金项目(12404445)

详细信息

作者简介:
胡江川，toyle@163.com

中图分类号: TQ171.6
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- 被引次数: 0
出版历程
- 收稿日期: 2026-01-14
- 修回日期: 2026-04-19
- 录用日期: 2026-03-17
- 网络出版日期: 2026-05-07

Investigation of the material removal mechanism in chemical mechanical polishing of YAG crystals using acidic polishing slurry

Laser Fusion Research Center, CAEP, Mianyang 621900, China

摘要

摘要: 针对高功率激光器件对增益介质表面质量的严苛要求，本文以钇铝石榴石(YAG)晶体为对象，开展酸性化学机械抛光(CMP)工艺优化与机理研究。YAG晶体因高硬度与低断裂韧性，传统方法难以兼顾高材料去除率(MRR)与超低表面粗糙度(Sa)，制约了其在高端激光系统中的应用。通过正交实验设计，系统考察压力、转速与抛光液浓度对抛光响应的主效应与交互作用，揭示了MRR与Sa主导因素分异规律：MRR受压力主控，Sa由抛光液浓度主控。基于该规律提出“去除-质量双响应参数解耦匹配准则”，并成功寻获协同最优工艺窗口(A3B2C2：110 kPa，4 r/min，体积分数10%)，实现MRR达30 nm/min，Sa低至0.14 nm，PV值0.04λ，表面零缺陷。MRR较现有$ {\text{SiO}}_{2} $磨料工艺提升11%，Sa低于Nd:YAG应用阈值(≤0.2 nm)。机理研究表明，酸性CMP中H⁺优先攻击$ \text{Al-O-Al} $键，诱导表层$ [{\text{AlO}}_{4}] $/$ [{\text{AlO}}_{6}] $单元重构与晶格畸变，XRD峰展宽与XPS中Al 2p结合能正移(73.46 eV→75.23 eV)共同证实表层发生非晶化转变与$ \text{Al-OH} $水合层生成，形成“质子介导-键选择性断裂-界面成键-软化层剥离”四步去除机制。在此基础上，首次提出“化学-机械时序匹配度”(CM-TM)理论框架，将CMP表面质量控制从参数寻优层面提升至反应动力学与力学去除的协同调控层面。本研究为YAG及同类硬脆光学材料的子尺度无损加工提供了系统的工艺准则与机理解释，兼具理论价值与工程指导意义。
- YAG单晶 /
- 化学机械抛光 /
- 表面粗糙度 /
- 酸性抛光液 /
- 材料去除率
Abstract: Background
Yttrium aluminum garnet (YAG) crystals, used as gain media in high-power laser devices, require stringent surface quality. However, their high hardness and low fracture toughness make it difficult for conventional polishing methods to simultaneously achieve a high material removal rate (MRR) and ultra-low surface roughness (Sa), which limits their application in advanced laser systems.
Purpose
This study aims to investigate the process optimization and underlying mechanisms of acidic chemical mechanical polishing (CMP) for YAG crystals.
Methods
An orthogonal experimental design was employed to systematically evaluate the main effects and interactions of pressure, rotational speed, and slurry concentration on polishing responses.
Results
The results revealed that MRR is predominantly controlled by pressure, while Sa is primarily determined by slurry concentration. Based on this finding, a "decoupling matching criterion for removal-quality dual-response parameters" was proposed, leading to the identification of an optimal synergistic process window (A3B2C2: 110 kPa, 4 r/min, volume fraction 10%). This optimized process achieved an MRR of 30 nm/min, an Sa as low as 0.14 nm, a PV value of 0.04λ, and a defect-free surface. The MRR represents an 11% improvement over existing SiO₂ abrasive processes, and the Sa value is below the application threshold for Nd:YAG (≤0.2 nm). Mechanistic studies indicated that in an acidic CMP environment, H⁺ preferentially attacks Al–O–Al bonds, inducing surface reconstruction and lattice distortion. The broadening of XRD peaks and the positive shift of the Al 2p binding energy in XPS (from 73.46 eV to 75.23 eV) confirmed surface amorphization and the formation of a hydrated Al–OH layer.
Conclusions
These findings establish a four-step removal mechanism: proton-mediated action, selective bond cleavage, interfacial bonding, and softened layer stripping. Furthermore, a theoretical framework termed “Chemical–Mechanical Temporal Matching” (CM-TM) is proposed for the first time, elevating CMP surface quality control from parameter optimization to the synergistic regulation of reaction kinetics and mechanical removal. This study provides a systematic process guideline and mechanistic explanation for atomic-scale, damage-free polishing of YAG and similar hard and brittle optical materials, offering both theoretical value and engineering guidance.
- YAG single crystal /
- chemical mechanical polishing (CMP) /
- surface roughness /
- acidic polishing slurry /
- material removal rate.

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图 1 不同压力、转速、抛光液浓度下的去除率和粗糙度

Figure 1. MRR and surface roughness (Sa) as functions of pressure, rotational speed, and polishing slurry concentration

下载: 全尺寸图片幻灯片

图 2 YAG晶体分别在抛光液中浸泡4 h后的表面粗糙度(Sa)

Figure 2. Surface roughness (Sa) of YAG crystals after 4 h immersion in slurry

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图 3 A3B2C2抛光工艺下YAG晶体的表面质量

Figure 3. Surface quality of YAG crystal under A3B2C2 polishing process

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图 4 YAG抛光前后XRD图谱

Figure 4. XRD patterns of YAG before and after polishing

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图 5 YAG晶体加工后XRD材料匹配情况(红色圈中结论为未找到匹配材料NO match Found in the search)

Figure 5. XRD material matching after YAG crystal processing (conclusion in red circle is NO match found in the search)

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图 6 YAG晶体加工处理前后的XPS图像

Figure 6. XPS spectra of YAG crystal before and after processing

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表 1 工艺参数和正交水平

Table 1. Factors and levels used in the orthogonal experimental design

level	pressure/kPa(±5%)	rotation speed/(r/min)	polishing slurry concentration (slurry: $ {\text{H}}_{2}\text{O} $, vol%)
1	22	2	1:3
2	55	4	1:10
3	110	6	1:15
4	160	11	1:20

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表 2 抛光液浓度与pH值的对应关系

Table 2. Correspondence between polishing slurry concentration and pH

serial number	polishing slurry concentration (vol%, slurry:$ {\text{H}}_{2}\text{O} $)	pH value
1	1:3	4
2	1:10	4.35
3	1:15	5.11
4	1:20	5.32

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表 3 工艺参数正交实验结果的平均值和范围

Table 3. Average and Range of Orthogonal Experiment Results for Process Parameters

index	pressure A (MRR)	rotation speed B (MRR)	concentration of polishing slurry C (MRR)	pressure A (Sa)	rotation speed B (Sa)	concentration of polishing slurry C (Sa)
K(1，j)	15.30	10.57	39.80	0.80	0.94	1.24
K(2，j)	16.10	19.63	34.10	0.58	1.02	0.89
K(3，j)	24.53	31.03	18.57	0.77	1.08	1.36
K(4，j)	51.50	46.20	14.93	0.92	1.36	0.91
ΔR_j (MRR)/(nm /min)	36.20	35.63	24.87
ΔR_j (Sa) /nm				0.35	0.42	0.47

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表 4 YAG晶体加工前的XRD参数表

Table 4. XRD parameter table of YAG crystal before processing

#	2θ/(°)	d	I(f)	(hkl)	θ/(°)	1/(2d)	2pi/d
1	20.934	4.2400	6.0	(001)	10.467	0.1179	1.4819
2	24.032	3.7000	45.0	(101)	12.016	0.1351	1.6982
3	24.164	3.6800	40.0		12.082	0.1359	1.7074
4	26.506	3.3600	25.0	(210)	13.253	0.1488	1.8700
5	26.831	3.3200	20.0	(111)	13.416	0.1506	1.8925
6	30.916	2.8900	4.0		15.458	0.1730	2.1741
7	33.536	2.6700	40.0	(220)	16.768	0.1873	2.3533
8	34.195	2.6200	100.0	(211)	17.098	0.1908	2.3982
9	34.604	2.5900	30.0		17.302	0.1931	2.4259
10	35.743	2.5100	25.0	(300)	17.872	0.1992	2.5033
11	39.855	2.2600	4.0	(221)	19.928	0.2212	2.7802
12	40.605	2.2200	16.0		20.302	0.2252	2.8303
13	41.784	2.1600	25.0	(301)	20.892	0.2315	2.9089
14	42.611	2.1200	20.0	(002)	21.305	0.2358	2.9638
15	44.141	2.0500	16.0	(102)	22.070	0.2439	3.0650
16	45.401	1.9960	4.0		22.700	0.2505	3.1479
17	45.985	1.9720	4.0	(112)	22.992	0.2535	3.1862
18	48.957	1.8590	40.0	(321)	24.479	0.2690	2.3799
19	49.353	1.8450	30.0	(202)	24.677	0.2710	3.4055

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表 5 YAG晶体加工后的XRD参数表

Table 5. XRD parameter table of YAG crystal after processing

#	2θ/(°)	d	BG	height	1%	area	1%	FWHM
1	35.212	2.5466	1352	160	0.1	6206	0.3	0.432
2	35.656	2.5160	1360	163	0.1	5446	0.2	0.372
3	37.385	2.4034	1407	590	0.3	9504	0.4	0.179
4	38.289	2.3488	1439	162	0.1	13474	0.6	0.926
5	40.175	2.2428	1509	559	0.3	25081	1.1	0.500
6	41.551	2.1716	1552	172797	100.0	2292149	100.0	0.148
7	42.768	2.1126	1572	395	0.2	24392	1.1	0.688
8	43.319	2.0870	1574	281	0.2	18365	0.8	0.728
9	43.830	2.0638	1570	257	0.1	16345	0.7	0.708
10	44.524	2.0332	1555	226	0.1	13375	0.6	0.659
11	45.573	1.9889	1509	172	0.1	13951	0.6	0.903
12	47.735	1.9037	1321	155	0.1	6704	0.3	0.482
13	48.114	1.8896	1287	138	0.1	9365	0.4	0.756
14	48.625	1.8709	1247	159	0.1	9975	0.4	0.699

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